Yeah, I think docker has its perks. It makes it easy to deploy stuff and all. It's also great if you are running a VPS with multiple services and you don't want to deal with those services conflicting with each other.
That said, I just think that a relay that's designed for small groups should be as simple and straightforward as possible. Not relying on docker for deployment could reduce the maintenance overhead and headaches while troubleshooting.
There are bunch of relays out there but most of them are in the very early stages of development. I think most relays use either one of the three: nostr-rs-relay, strfry or nostream.