I do have a 4k tv, and a 1080p one. But personally I don’t see big difference on 720p vs 1080p vs 4k. I have to be like 4 feet from the tv to notice it. 720p is sufficient.

I have a similar setup. I have an old laptop with an SSD that puts files on my NAS. The laptop has arr setup on containers, the laptop itself is running debian, mounts from Samba NAS via fstab (be sure to have writing permissions) has been working that way for several years.
Only direct plays, no transcoding (core 2 procesor)