I have been using an old PC as NAS and running docker containers (Immich, Nextcloud, paperless-ngx etc.). I got 5 3.5" HDD disks and a Nvme. Even on idle, I am consuming 50-60w. A friend of mine is selling a Qnap NAS which is a dedicated machine and probably consumes less power, although I don’t know if it’s worth it.
I wonder if they can be “spinned down” like hard drives. their startup time would be much faster, so it’s shutdown could even be on a tighter schedule. I mean probably they dont have an internal idle timer, but who cares if you can just have something like hd-idle that shuts it down according to a better schedule.