You start with computers built with Linux in mind. There are a couple. Usually though, it is best to go through the hardware items, Googling something like, “XXX hardware device & Linux.” Open source support is always a plus.
And the ArchWiki cannot be overlooked.
EDIT: It is very rare that Linux doesn’t support hardware, the more common the better. The support may be limited, since Open Source coders don’t usually get access to closed-source hardware support software. Linux kernels are aces, though. New kernels pick up new support with every iteration.