I’m self-hosting a Piped server, and it’s working great. I was able to import my YT subs from a Google Takeout dump, and I continue to add more channel subs on the Piped server. So far, no YouTube ads, plus it uses SponsorBlock, so I can skip that content too.
For mobile client, LibreTube is working quite well for me. It talks to my Piped instance, so subs (but not watched history, unfortunately) are maintained on the server. I’m still looking for a Piped client for Chromecast GTV to complete the ensemble for me. Right now, I still use my YouTube account with SmartTube Next (which also avoids YT ads and uses SponsorBlock).