I'm still shocked that my google voice number still functions after all these years. It makes me assume it's main purpose is to actually be an honeypot of some sort, maybe for spam call detection.
My guess is it just keeps chugging along with little maintenance needed by Google itself. The UI hasn’t changed in a while from what I’ve seen.
I have a tiny service built on top of Google App Engine that (only) I use personally. I made it 15+ years ago, and the last time I deployed changes was 10+ years ago.
It's still running. I have no idea why.