literally was going through the exact same thoughts as you a couple a weeks ago, tried so many different configurations but the one i found that worked was actually kinda simple

basically they way i did was to run a gluetun docker container, and then in the environment variables pass in the the fact i wanted this to use the WireGuard VPN manager, and then i passed in my Proton VPN wireguard api key (you’ll need a subscription for this)

then once that gluetun container is up and running, you literally just add “network_mode: service:gluetun” to any other containers that you want to use this VPN

can you can even test its working by sending a curl command to an ip checking site from within those containers connected to gluetun