Opinion on this property (buy or wait)

Hello,
a brief introduction about us:

Married couple, late 50s, children have left home, want to move from the city to a more scenic area.
But at the same time, there should be a doctor and shopping options within about 3 km in the new home.
Children are (almost) out of the house, so planning can start now.
Professionally (home office etc.) no problem, financially also not.

So far, our plan was: prefabricated house, 2-story without a basement.

Now we have the chance to get a plot of land (500 sqm) in a nice small town.
The only "disadvantage" here is that this plot is on a slope (upwards)
(after the 3m slope there is only a slight incline which would be/is manageable):
Either build with a retaining wall (or retaining walls), or with a basement (recommendation from the architect after a short inspection). This means that the main entrance or living floor can only be reached by stairs (inside or outside) or by an outside path with an incline (plus about 6 steps).

It should be our last "move," we are just unsure whether these necessary "stairs" (or path with incline) will hinder us so much in old age (>80 years) that we will have to look for something new after all (via the planned basement access a lift could still be installed, but... hmm).

Currently, plots (close to the city, with some infrastructure) are not so easy to get.
In addition, many communities award new plots according to "social points" (children, foster parents, local residents). Even though by law this should no longer be solely decisive, having achieved "0 points" (which applies to us) means you are almost hopeless.

Other plots we had as "options" had steep slopes, power lines right next to them, forest edge (shade all day), street noise all day, ...)

Advantages (*) of this plot are:
No street noise to be heard.
Fair price.
- 400m bus stop
- 1400m to city center
- 1600m to old town
- 2000m to train station
- 2200m hospital
- 3000m Lidl, Aldi
- 6000m hardware store

The plot is located in a building area, about 12 houses already stand, further up a new building area with 20 houses will be built next year (completely uncertain whether we would have a chance there!) And waiting that long is also not an option, either buy now or someone else gets the plot.

Actually, everything fits with the plot (see *), only the basement (including additional costs about €70,000, although the money is not gone but only "invested"); and the access to the house (path with incline plus some steps) still worries us a bit.
Outdoor stairs and path must be cleared in winter, e.g., with age...

What do you think? Any suggestions, experiences or "thoughts" are welcome.

Use the possibly unique opportunity for an almost "perfect" plot?
Or hope, and rather build single-story for old age?

Isn't it possible to build the garage on the ground floor with a passage to the basement and either space for a lift in the house or to build stairs that will be stairlift-friendly. The garage roof will then become the terrace ...

I believe you don't need any suggestions, just a confirmation of your gut feeling that this is THE property ;)

Steps, path, etc. are just really small "issues".

My subjective opinion: If everything else fits, I would take the property. As a person of your age, I permit myself the not entirely serious question, how much longer do you want to wait for the more perfect property? ;-) What speaks, in the worst case, against an elevator or how do you already know now that when you are >80 you wouldn't rather want to live in a senior center right next to the opera/concert hall and a Tchibo standing café? (That is my dream scenario, not yours. ;-) )

Please do not take my contribution as disrespectful; I am the same age as you, we are currently building new (prefabricated house with timber frame construction) and I hope that my final destination will rather be the senior center right next to the opera/concert hall and a Tchibo standing café. :)

Can't the garage be built on ground level with a passage to the basement and either space for a lift in the house or stairs built to be stairlift-friendly? The garage roof will then immediately become a terrace ...

The garage is planned at the basement level. The entrance to the basement is planned next to the garage (or through the garage, which in my opinion is not so practical). And the garage roof is planned as a terrace (well thought out, thanks). And yes, we are really unsure whether the necessary steps (or path) (to the ground floor) will be a problem or just a small "issue" in a few years. With a stairlift from the basement to the ground floor, it should still be livable in old age (as long as one partner is still reasonably fit).

Married couple, late 50s, children have moved out, want to move from the city to a more scenic area.

Ah.....life can begin :D

But at the same time, in the new home there should be a doctor and shopping facilities within about a 3 km radius.

I would give the cyclist a bit more freedom. As long as you need a doctor’s visit, shopping, etc., you won’t be walking 3 km either. If you’re already in the car/taxi anyway, 10–15 km can be fine as well; then you just drive 7 instead of 3 minutes.

Professionally (home office, etc.) no problem, financially also not.

That’s already good.

The only "disadvantage" here is that this plot lies on a slope (upwards)

Depending on the planning, such a "disadvantage" can also become an advantage. I wouldn’t buy an off-the-shelf house but have something individual planned, and once have an interior architect take a look. I think the right basic idea must come first, and for that, you need your needs and wishes as information or your way of life.
We have now built a house for the two of us with an option for (children’s) visits. For ergonomic reasons, a bungalow was considered, because this type of construction gives the impression that one could live there easily until the last breath. If you then have wider doors and can install a lift, everything fits..... if it doesn’t, that’s my opinion.
First, there is the time UNTIL "then," and you want to live as nicely as possible during that time. Luckily, nobody knows what "then" will look like. From my family experience, I see it this way: ultimately, you can bring in technical improvements almost everywhere so that you can live there when you are older. The main problems I experienced were mental—that the person developed cognitive deficits or weaknesses. I believe that, similar to security technology, home builders are given a kind of security that actually doesn’t exist. That’s why sales of security technology skyrocket, and hardly anyone is really safer or actually in danger.
Of course, you don’t want to move anymore, but life doesn’t care; my mother moved again at 83 because it fit better into her life.
If you can no longer climb two steps, you can’t move safely on flat ground either. The worst falls I experienced were caused by slipping in the wet bathtub, on a doormat only 5 mm thick, on alternating floor coverings (carpet on parquet), or simply due to sudden dizziness. The always feared things did not happen, as is often the case; the danger lies in the assumed safe area.
That said, you can still plan in advance to make it easier or more spacious. For example, my mother later had a very small shower bathroom, which she preferred over the big one she had before. She could hold on to all sides.
In addition, I prefer to live true to the statement of my former colleague: "If already into the abyss, then please in the S-Class."
We absolutely didn’t want to move into a housing estate again and have now ended up there again, with 7 other small houses, although we live at the end of the dead-end street.

Outside stairs and path must be cleared in winter, e.g., with age ...

If you start there... once you are old, you don’t need to clear anymore, the care service will come to you anyway, and if you are cared for/supervised, you don’t want to go outside in nasty weather anyway.

Use the possibly one-time opportunity for an almost "perfect" plot?

Yep

Or hope and rather build single-story for old age?

...or wait until old age is here and then build according to the respective complaints, which will be different at the start of construction than after completion, leaving you again at the beginning of the question.

One can also see all this exactly the other way around; it is probably a question of one’s own life philosophy. I would listen closely to myself and build a nice, compact house together with experts, in which I am happy every day that I built it exactly that way.