I recently moved a lot of my services off my daily driver onto what will become a NAS.
I settled on Void because it has such good support for ZFS. If you’re going to use ZFS, I would recommend Void.
Arch can be a bit unstable but it’s simple to work with so that’s an option.
If you run things in docker containers it shouldn’t matter anyway, so ultimately pick something you’re likely to use outside your media box, that way you’ll be able to maintain it better.
As for remote access, I have a separate machine running alpine with wireguard in a docker container, I VPN into that machine to get access to other devices in the network.