I’d strip it, I usually end up selling frame, wheels, forks, and anything of value like brakes if they’re decent, drivetrain if not worn, etc. Ebay, facebook or the classifieds depending on how big I reckon the market might be for it. Older or niche stuff does better on facebook or classifieds as it can sit there until someone who wants it finds it. Ebay works best if it’s something that you know for sure several people will be searching for every week. Most of the time that gets more than the complete bike price just from those parts, I know if I’m bidding on something I’m toting up the value of the bits I don’t have spare, i.e. those few big ticket bits, so I guess others do the same.
Smaller parts I tend to transfer to the next bike as pedals, grips, bars, saddles are all personal preferences.
Drivetrains I tend to transfer as part worn stuff is never worth as much as it’s remaining life, a 50% worn GX cassette is basically valueless, but is “worth” £50.
Misc small parts end up in the spares bin and if that overflows they either get given away in the cycling club.