I’ll echo the rest of the comments and say Debian with docker. I use podman myself but the setup should be similar enough. I used the official Jellyfin guide from their wiki and got everything working in a day, including transcoding.

The B650M is a smaller size and therefore has less features, but overall they seem similar. Biggest difference would be the integrated SSD heatsink and better VRM design + cooling of the non-M version. Also the second SSD slot being connected to the CPU instead of the chipset, if you ever want to put in two M.2 drives. One thing to watch out for is that both of these boards use a Realtek LAN chip which sometimes can be problematic with Linux.

VRMs (voltage regulator modules) are what bring the power to the CPU and these can get quite hot on high power processors. If you look around the socket on a motherboard, usually above and opposite the RAM, they are the big square/rectangle shaped components. Most high-performance motherboards have heatsinks on top of them to keep them from overheating, which your MB does not have.

Poweramp for music also. Worth the price, you can also skip the Play Store by buying it on the dev’s website if you prefer

Well, Win10 Home and Pro EOL is late 2025, so it’s tecnically correct…

Modern Gnome should in theory be able to adapt to any (reasonable) display size. So anything with recent enough repos would be a good fit