I just had my 10 year old MB literally fry that I had my Plex on so I bought a new Intel NUC.

https://www.amazon.com/dp/B09KNK3R29

I was lucky and got that model at the $740 barebones price though. I did take the 1TB drive out and pop in a small 256GB SSD. I only run Plex on this device. Idle it uses 8-10 watts. It almost never goes over 15W usage. Maybe spike to 20-25 if Plex is doing some video/audio file updating and scanning.

Tested and it was able to handle 7 4k to 1080p transcodes at the same time. The primary CPU doesn't do much so it doesn't even warm up. This little NUC could handle so much more.

I run Ubuntu on it. I don't use Docker but could and would if I also wanted to run other services on it at the same time.