>>9427any thinkpad compatible with libreboot, or some dell latitudes are compatible too. I'd get an X200 or T400 if you want total freedom, or a T430/X230 if you want more performance and 99% freedom (because of the intel ME you can't fully remove on those newer models, you can only 'disable' it and strip it down to a ~70K stub)
the T430/X230 (aka XX30 models) have worse build quality, a raisinty keyboard, and not a much better screen than the older models, but the good thing is that you can replace the CPU, RAM, storage (msata ssd, sata ssd, ultrabay for a sata ssd/hdd or a cd/dvd drive, expresscard slot for an nvme adapter, and so on), keyboard, display, etc…
you can replace the screen with a newer T440p IPS panel, they look a lot better; and for the keyboard, get an X220/T420 keyboard, file down some metal tabs, cut off some plastic from the frame, isolate some contacts with kapton tape, flash a modified EC firmware, and you can use a proper non-chiclet-garbage keyboard in XX30 models as well. I have a bunch of X200's, T400's, T60's, an X200s and X200t, and a T430. All of them are fully upgraded, and each one will cost you about 200-300$ if you want good storage (4-8TiB of ssds and hdds)