Fixed interest rate for the entire term or only 10 years?

I would mainly be interested to know if it makes sense to spend €70,000 more from the start.

That depends on the conditions. Just post them. Land. The statement that it is always pointless to spend more. Or do you also deliberately buy the most expensive goods in daily life? P.S. What does the subsidy have to do with the loan amount? You don’t get the allowances at the beginning. If you have to pay €500,000, you have to have €500,000 available TODAY and not only in the coming years. No one can say whether they consider subsidies or not. Do you even understand what you are doing or have been offered?

...how is anyone supposed to help you here if you don't specify the conditions? Your calculation is already flawed because you are comparing two different loan amounts with the same installment amount. I simply doubt your calculation. Therefore, nothing can be said about your financing, only in general that security costs money.

Completely insufficient information. In addition, apples are apparently being compared to pears. What is one supposed to say about that?
Besides, you should be able to understand your contract. If not, that is a good reason to choose another one.

We only need €475,000. I have requested higher offers to have a buffer. I actually just want to know how you feel about fixed interest periods. Is 10 years okay or should I definitely go for the full repayment over 30 years? And to better illustrate my offers, I have given you the total costs. I can also provide interest rates, but then you still wouldn't know anything about the fees. For example, Bank 2 is 0.1% cheaper for us than Bank 1, but overall more expensive with the savings contract by €5,000 and after 10 years there is an outstanding debt of €190,000. Nominally they are cheaper but I would fare much worse. That's why I am only giving you the most important information. I just can't decide if it makes sense to spend €70,000 more

Ultimately, only you yourself can decide that.

If your calculations are correct (which we have to assume), option 1 is clearly the cheaper one. BUT it is associated with a manageable residual risk.
This residual risk can of course be massively reduced through special repayments. Whether you can and will do that, only you know.
With the building savings contract, however, you also have the option of special repayments, especially in the repayment phase, I even think in any amount. But I’m not sure about that now. At least that’s how it is for me.

You see, no one can give you very good advice here because not all conditions are known.

Ultimately, option 1 is clearly cheaper but is associated with a (relatively low) residual risk.
Whether you want to take this risk or if you can possibly almost completely eliminate it with special repayments, only you know.
You have all the facts, so you have to decide what is better for you.

I would choose option 1, but I assume that special repayments are also possible here, which I would probably use then. Whether you do that, again only you know....

Sorry, but you don't seem to quite understand. Your calculation is not comparable and I even believe it is wrong. The numbers look like this at first glance. When comparing, many aspects matter. By that, I mean mathematically. And one or another could help you here. But it doesn't work that way. The question of whether 10 years or longer depends a lot on your personal situation, the structure of the loan, etc. However, despite multiple hints, you either don't seem to understand it or you don't trust anyone here to understand it, so I'm out now. No offense, but your question doesn't make sense like this.