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.
Ram is definitely abysmal on Qnap, so it’s one reason for hesitation. But I wanted to get some idea how much power saving is possible on dedicated NAS. If it’s not much, I would rather keep my PC.