I (very much an amateur) briefly tried TueNAS scale in the past and didn’t like how they did apps. So I switched to Openmediavault, which since then has served me very well.
With a plugin I could easily add my zfs raid and I use their build in docker compose gui to run the few programs I need.
I didn’t try out others, but there are more options. CasaOS and yunohost already got mentioned, there is also Cosmos or just running a basic server with e.g Debian and maybe adding Cockpit for some management gui.
I guess if you want specific recommendations you need to define your needs and requirements a bit more.
Since I was wondering if Cockpit is an option for immutable distros I stumbled on this video, which seems to suggest it might since it is used on one there. So I guess you could pick your favorite immutable distros and see if Cockpit works to have a easy gui for managing the server stuff.
You could of course also go for something like NixOS and make everything declarative.
For me Openmediavault was easy to set up and just works for the little stuff I want it to do.