When you say “couch” my first thought is a recent-ish Celeron or Pentium Silver fanless laptop. Performance akin to a Core 2 Duo but no fan to get blocked sitting on the couch. Like the Latitude 3210(?)
Laptops that appeal to me are often bottom breathers so it’s one thing I miss from my old MB Air.
iTunes will probably be the toughest. I lean on iTunes for syncing files, media, local backups and if I had to ditch Windows tomorrow and decided Linux, I would set up iTunes in a Windows VM since I don’t think there’s any other workaround currently.