My vote is also on Proxmox. I also started out with a mini PC about 6 months ago and installed proxmox. It has a few quirks regarding its disk usage you have to get used to, but its UI and setting up of VMs and LXC containers is so simple, you do not need any manual. You can easily build and tear down linux machines and play around with them. You cannot run docker images directly, but I use an LXC ubuntu container to run them, works flawlessly.

I’d recommend Debian Linux. It’s free, stable, has all the software you’ll need with long term support, ton of online resources and communities to learn from. You can start with or without UI.

Sounds like you’re just starting out. If you’re not yet familiar with Linux there’s a lot guides out there to set this up & it won’t take take long. It’s when things go wrong it can be frustrating as it possible there won’t be a guide for your specific issue & it can be time consuming to figure it out.

You could start just using windows if that pc came with it. It’ll enable you fast track the fun of building & populating the media server.

Over time you’ll discover the limitations of windows, start researching the alternatives & have plenty of time to pick something else while enjoying what you’ve already setup.

I recommend debian 12 works like charm

I have been on this path (10+ years in)

• windows server
• FreeNAS > TrueNAS
• Proxmox
• Bare metal Debian with all Docker containers

I learned the most with Proxmox (and ZFS), everything in LXCs.

But I enjoy the pure Debian install with Docker containers the most!

Ps: do not, I repeat, do not install a desktop OS. Pps: stay away from Ubuntu ;)