Are there enough offers with us (Brandenburg) for a 130 sqm house for €250,000? Look at, for example, EWA Bau from Potsdam. So in Brandenburg, this is possible without problems.
€1,500 for a nurse must be very part-time without many overtime hours. The base salary for beginners is currently about €3,000 + allowances for, e.g., intensive care and supplements for night/public holidays, etc. That means you can already earn around €4,000 full-time. All hospitals have to/should pay this, keyword Pflegestärkungsgesetz.
I find the financing very risky. Whether a bank grants a loan with a fixed-term contract is difficult...