Acquiring an ET apartment as a capital investment

Hello everyone,
I’m sure there are one or two among you who can give me some suggestions / tips.
I am about to buy a small one-room apartment (balcony, parking space, cellar, elevator) as a capital investment (approx. 41 sqm for 89TE, good condition, no renovations necessary at first, no realtor, rented, good location), current rent is 340 euros net cold plus 110 euros additional costs, house money 38 euros.
Considerations:
A- Use a lot of equity so that no loan has to be taken out
B- Use little equity in order to benefit from low interest rates and to use the equity elsewhere in the next few years (we want to buy a single-family house or a condominium with a garden) and invest part of it in, for example, a fund savings plan.
The total amount of 89TE is manageable, but I cannot assess whether a one-room apartment is worth that, or whether the return on such an apartment generally pays off, considering effort and costs.
If I take out a loan, should it be based on the net cold rent (plus reserves) so that the property "basically pays for itself"?

A brief note about myself:
permanently employed, approx. 2600 net (just for info: plus 13th and 14th salary plus annual bonuses)
married, 1 child, my wife is currently on parental leave and I would not currently include her in the financing (just for info: approx. 2600 net after parental leave)

This area is new territory for us, so we want to make appointments with various banks in the next few days to get an impression.

Regards and thanks for your tips

Simply put, you will have recouped your capital after 25 years of pure rental time. In addition, there are maintenance, repairs, tenant changes, vacancies, and not to forget the tax on the income. If you have a loan, the interest can reduce the tax burden.

I am not an expert in the field, but that does not sound worthwhile to me. Especially since you actually need your money yourself, so why tie it up if no profits are expected there in the near future?

Wasn't there a rule of thumb of 20 times the net cold rent?

I'm not an expert in the field, but that doesn't seem worthwhile to me. Especially since you actually need your money yourself, so why tie it up if no profits are expected there in the near future?

Yes, that's why I want to use as little equity as possible and preferably repay at a rate of 1.2-1.5% over 10-15 years plus Sonti.
I know that "one" apartment is a concentrated risk, but I want to build another pillar (we are already investing long-term in funds and saving in the daily money account plus 3 building society contracts).

One way or another, you have tied up your capital, either spent it on the purchase or as a monthly burden. Both are likely to noticeably strain your single-family home financing.

With an apartment in the [Münchner Zentrum], the bank of course applauds, but your numbers don’t sound like that. Otherwise, I have found that these "rental income" do not really make banks positive.

For the majority in the forum here, the following applies: We cannot pay for a good condominium and a good single-family house out of petty cash and have to finance both. So if one of them is not "just doable," why tie yourself down with both at the same time.

In your situation, investment types would be prioritized for me where I can generate profits over the investment horizon and still be able to release the capital in the medium term.

If you already had an almost paid-off house, I would say buy it, if other parameters also fit. But you either have to bring in your own capital and/or pay interest. You bind yourself for 20 years or more and have nothing for a future single-family house. Only debt. With a house fee of €38: what is the year of construction? How many units?

Edit: the salary is not really the best for an investment, even if it has good conditions.