It’s not a “normal” vpn client. It allows you to create a network in your server using a variety of vpn providers so other containers can use it to connect to the internet. You use tailscale to connect to your server from outside home, but you use gluetun for your containers to connect to the outside world without exposing your real IP.

So yes, tailscale and gluetun are compatible and can live together (I use both on my homeserver)

Tailscale allows you to do the same except you can create keys with limited access to only certain ports (just in case you don’t want them peeking around your server).

If it’s for your personal use and no one else is going to connect, why don’t you just configure a wireguard tunnel to remotely connect to your server as if you were in LAN without exposing anything?