Nice! … how exactly, I wanna know :)

I have my nextcloud server exposed, I keep it up to date, patched, etc. but I’d love to use the extra protection of a VPN. Just … I don’t think mobile apps work very well with that, unless I keep my phone constantly connected to the VPN, right? Or is there a smart way to do that?

I don’t think you’re out of touch, just use docker compose. It’s not that hard to conver the docker run example command line into a neat docker-compose.yml, if they don’t already provide one for you. So much better than just running containers manually.

Also, you should always understand what any command or docker compose file does before you run it! And don’t blindly curl | bash either, download the bash script and look at it first.