How to (safely) create a Lemmy instance?

Basically, I want to make one for some multiplayer games out there (along with Stoat communities, or something similar - what do y'all recommend? Bonus if it has voice chat).

What would I need, and how can I set this up safely without having my own network hacked beyond comprehension? I could do it off site from home too if that's better.

I have a Raspberry Pi 4gb, but also an old DDR3 16gb desktop with a PCI network card available if that's recommended.