That's also my plan

However, I have one worry... To borrow money, take a loan, using Bitcoin as a collateral, I will have to give up on self custody, right?

The future lending institution that will lend me money, will need to get control over my Bitcoin, right?

So that they can sell it in case I do not pay back...

Unless there is going to be sone multisig future solution, I guess.

But even then, it will not be trustless anymore. On the other hand, how could it be, if I want someone to give me money...