...With the financing amount (why don’t you have any equity?) you will – if at all – only get a bad condition. I calculated with 3.5% interest/repayment. That’s already €1,550 just in installments. ...
I am financing alone, but I have a similar net income as the OP with a partner.
I paid the incidental purchase costs with equity, everything else through financing. This also means 100% financing with almost €2,100 per month in installments. Repayment around 3.09% p.a., mixed interest rate (since 2x KFW and 1x house bank) is 1.35% effective per year. I find that anything but bad for 100% financing. And that, as said, through my house bank and not through any online banks.