In terms of WiFi cards you can look on https://h-node.org/ for stuff that's compatible with Trisquel and other FSF-approved GNU/Linux distros out of the box. I use the Atheros AR9285, they are less than $10 USD on AliExpress (if you're okay with buying from there, of course). If the laptop has Libreboot/Coreboot it will work fine.
T500/W500/R500 is the "most recent" 15" laptop compatible with Libreboot but
they are still 10 years old, not going to find it new anywhere. Maybe
consider a T530 or T540 with Coreboot? Can put quad-cores in there too, but
either way still going to have to find it used.
- [Trisquel-users] Notebook 15.6'' for LibreBoot 500 usd ... znavko
- Re: [Trisquel-users] Notebook 15.6'' for LibreBoot... xliang9550
- Re: [Trisquel-users] Notebook 15.6'' for LibreBoot... jason
- Re: [Trisquel-users] Notebook 15.6'' for Libre... thum+trisquelforum
- Re: [Trisquel-users] Notebook 15.6'' for LibreBoot... arc