This is how it looks, 99.9% of banks do not make a final offer if they do not have a written award from the district court.
Of course, you can roughly estimate the award for what you can auction it for, then there is also an "offer" which is roughly estimated and of course non-binding.
For a self-employed person, banks also deduct many expenses that you currently do not have! You say that hardly anything is done for retirement provision? That's why you have 1,700 EUR available monthly.
However, the bank will deduct 20% from the gross in the "background" calculation, so from the 3,900 EUR (like for employees, the employer's and employee's share to statutory pension), so on paper that is already 780 EUR gone...
then from the 1,700 EUR net only about 1,000 EUR remain, and with that no bank would be able to provide financing...
even if the bank only deducts 400-500 EUR for retirement provision here, then we are at 1,200-1,300 EUR, still far too little to finance 200,000 EUR...
PS. So if an employee earns 40,000 EUR gross per year, a self-employed person has to earn at least 50,000 EUR gross to have the same net!
Because for the employee, the employer still pays about 20% in social contributions for them (pension, health insurance, unemployment insurance, etc.)
As a self-employed person, you have to bear all that stuff alone.