So for Minecraft, I just found out the hard way that you do not want to run Minecraft in any sort of VM at all. If I had the budget to build a dedicated little gaming host, I would probably grab something like the Ryzen 5 3600x for a nice amount of thread overhead as you can run variants like PaperMC with Dynmap that actually can use more then a couple threads for certain tasks like chunk generation, networking and Dynmap web map generation.
I ran a Space Engineers server for a little while a few years back so I don't know how it has changed since then, but the server itself would not run without a GPU. Even worse was trying to start the server while using Remote Desktop failed to start as well.
There is also the upcoming Ryzen 5000 series CPU's coming on November 5th, assuming enough supply, that look very promising if you can wait.
So probably something like:
Any B550 board that has the I/O and slot configuration you need and decent VRM's (might be able to sneak in a B450, but less chance for good BIOS updates)
A Ryzen 5 3600x or wait for the 5600x if you can
Can always grab a 3600x now then swap CPU's later
4x 8GB of DDR4 RAM, anywhere from 2400 MHz to 3200 MHz, just check the Motherboard QVL for models that run with all 4 slots filled at that speed
Personally I'm running two kits of CMK16GX4M2B3200C16 on both my X570/3600x NAS server and my X470/2600x Gaming PC
Any low tier slot power GPU unless
If you have decent electricity costs, you could always look at something like the GTX 1050 Ti or 1650 and run Folding@Home on it too to help out with COVID-19 research
A good Power Supply
Personally I like the Sea Sonic Focus Plus Gold line-up right now, EVGA's B and G series have always been great to me in the past as well