While the Framework maybe isn't 100% Linux first, Linux is definitely treated as a "first class citizen": https://frame.work/linux with active (dedicated) first party support: https://community.frame.work/tag/linux

(Matt Hartley, the new Linux Support Lead was formerly providing technical support at System76)

I ended up going with a Framework last year as an upgrade since I liked the display (3:2 HiDPI 400nit+ 13.5") and form upgradability, but also because the official Framework forums was by far the best Linux laptop forum I've seen online. As long as you can deal w/ 5-6h of battery life, I can highly recommend it as one of the best Linux ultraportable laptops (although I'm really hoping that there's a Ryzen 7040 motherboard upgrade coming...). My review/notes on the 12th Gen Framework w/ Arch Linux: https://github.com/lhl/linuxlaptops/wiki/2022-Framework-Lapt...