Own effort - What can be sold well at the bank?

Hello,
I wanted to ask what can be considered as personal contribution at the bank. What makes sense and what can be included in the financing for that?
Oh yes, assume we are academics. I can manage to lay flooring, but I would like to stay away from electrical and heating work.
We are building a house in timber frame construction as a 1.5-liter house. That means, even for the insulation, it makes sense for the professionals to do it. However, we would like to contribute 25 - 30 thousand euros as personal contribution in the financing. Well, what do you think, where is that still possible?

If it is "only" things like laying laminate or painting, I would probably not set any amount for own work at all. Because you still have the material costs. And the time required should not be underestimated, and since it is in the final phase of construction, time is often pressing because the rental apartment has been terminated, etc.

Is that about 1.5 liters like the cars from VW?

Limit yourself to floor laying (without tiles and parquet) and painting work, excluding varnishing work.

Maybe also things like setting door frames and garden work (excluding paving work).

That way you might save about 5,000 EUR in the end, but with 200 hours you already have enough to do alongside your job and everything else.

25 to 30 thousand euros in personal contribution is already very, very much and hardly feasible for an average person. Or you have forever time.
Hardly any bank will accept that, unless you are a craftsman yourself.

We had 10,000 euros in personal contribution. The bank didn’t want or allow more.
In the end, we probably put in more personal contribution, but better that way than the other way around.

Addendum:

25TEUR corresponds to about 500 craftsman hours at 50 euros/hour. Normally, these are calculated with a factor of 2, maybe by the end you will become a more professional craftsman, simply because of the quantity and the increase in knowledge... so factor 1.5.

That makes 750 hours, which is just under 20 working weeks. Even subtracting annual leave, more than 3 months of work remain missing for you. Even if the partner helps.

Unrealistic, unless the vau is supposed to last 3 years.

Addendum:

That makes 750 hours, which corresponds to just under 20 working weeks. Even after deducting annual leave, more than 3 months of work remain missing for you. Even if the partner helps.

But if you also include brother, friends, etc., it is easier to accumulate the hours. And the time. Paving, the garden (dry stone walls, ...) can also be done when you already live in the house. Painting, floors, possibly doors, tiles in the basement I would definitely have calculated by now. Do you have any tips on what one can easily do oneself?