Functional? I still have that old 512 K Fat Mac that I wrote about resurrecting on the old TMF Apple boards. I think I put “vintage computing” in the post. It’s sitting in a closet. I have no reason to believe it eventually stopped working after I recovered it.
“Still use” is probably my old Macintosh “Pro Keyboard” from 2000. I think I got it with the Power Mac G4. I haven’t really liked the evolution of Apple’s keyboards over the years with their increasingly slim form factors and shallow key travel, so I’ve migrated that keyboard to successive Macs for over 20 years. Despite the years of pounding, it still works practically as new.