[JCattheATM]

> I still genuinely struggle to understand the advantage of UEFI/Secureboot whatever over BIOS.

Apart from way nicer boot menus and bootloader setup?

In a security context, it prevents a whole host of attacks, it's clearly an advantage and a much needed progression.

> Out there, there is software, which I have to figure out how I'm going to trust,

Yes, and with secureboot, if you guess wrong, that malicious software can do less damage than it otherwise could.