Prefabricated house or solid house companies - budget

In areas with such a low land value, I would look for existing buildings and then renovate. Existing houses are often almost given away there. It should be significantly cheaper than a complete new build. With that income, you really have to stretch yourself with a rate of over 500€.

Inventory is out of the question. Better to save and postpone the project. But at the moment, we are also paying a cold rent of 600 € and can live well despite various car repairs recently. We are very frugal but have not been employed for long enough to have built up equity. However, secure jobs are available.

With a financing of over 100%, the rate is probably around €1200, plus additional costs of roughly €300 – so you’re already at €1500 per month just for the house. It would probably be possible, but do you want that? A €300k plot of land and a small house, with [EL], is already possible... but also quite a high monthly burden.

As said, we are aware of the risks and will receive more precise calculations next week. Speculations don't help us much, better accurate experiences - not meaning this badly. And please don't focus only on the financing, but also on our "conflict" between solid construction and prefabricated house. We also need experiences there, as we are still completely uncertain about this.

We see great advantages in prefabricated houses ganz klar in the price (is that really so?)

And "ganz klar" if one still asks whether that is the case?
Please take your time and read through the forum here carefully... take your time... first of all: the answer to the question in the bracket is "no".

Speculations don't help us much, better precise experiences - not meaning this badly. And please don't just focus on the financing, but also on our "conflict" between solid construction and prefabricated houses

It is not speculation but a prediction. Experiences help little, or what good is the information if someone comes along saying "yes, we also built for 300k€" or "no way, we already paid 400k€ for a 120m² house without the land." The topic is so diverse and multi-layered that your question is way too vague to be able to target an experience. Solid construction and (wood) prefabricated houses are often compared from the wrong perspectives. The prefabricated house is usually more expensive with the same requirements. With your budget, in any case, a standard floor plan from the large general contractors comes into question, basically an off-the-shelf house. You can just go to a model house exhibition around the corner and have a look.