My oldest Apple device still in use is a late 2008 13” MacBook - the very first “carved from a solid block of aluminum” laptop with a door on the bottom that opens with a lever for replacing the battery. I lost count of how many batteries I’ve put in it. I upgraded the drive to a SSD and maxed out the RAM to 8 Gigs a few years back. I continue to use it because it is a lovely little machine that still works fine.
I tend to keep my computers and just repurpose them for a range of specific tasks when new faster hardware comes into my life - sort of a personal, cascading hand-me-down effect. Earlier this year I finally pulled the plug on an old G5 cheese grater from early 2004 that had been relegated to simply running Safari for browsing a handfu of amateur radio specific web sites in my ham shack when I was on the air.
My wife still has her original G5 too (not in use either) and we keep threatening to get a glass top and use them as the base for a coffee table.