Laptops from over 5 years ago are well supported by Linux (for the most part). However, the very modern laptops have bits and pieces that aren’t supported, from fan profiles, to the new intel webcams etc. They will run Linux, but you might fry them if your fans don’t work properly. So your best bet would be to get either an old one (I got a Macbook Air from 2015 with 8GB RAM, works great), or get a Tuxedo, or a System76 one, or a couple more Linux-specific ones. And it’s not because suddenly Linux does worse job supporting hardware, but it’s because these machines are. getting more complex and they need drivers for every little thing. Back in the day, things were more generic (e.g. the fans) and worked with a single driver.
Not the case with all laptops, e.g. some asus ones, and not even the tuxedo ones that require drivers.