wireguard is self hosted and you do have to “expose” one UDP port. From the outside it’s difficult to detect that this “opening” exists because wireguard just listens and ignores everything unless you send the encrypted credentials. Compared to hosting a webpage or jellyfin directly this is much more secure. As long as you keep wireguard relatively up to date you don’t really have to worry much about it.

I personally use wg-easy. It’s designed to be deployed into docker (using docker compose is by far the easiest).

Then you can either use your IP address, or ideally a dynamic DNS provider so you’d connect to myexample.com:51820. Duckdns is free, otherwise options are available like cloudflare. If you can get jellyfin working, this should be relatively straightforward.

For modern AAA games I’d say that’s pretty accurate of a recommendation despite the costs associated with ram. Ideally games should be optimized to run on 8Gb but windows and other software is probably going to happily eat up a few gigs.

Absolutely no problem with it being virtualized as long as you have a pci storage controller and pass that through to trueNAS. HBA cards can be found that do this without raid or anything so you can use zfs in trueNAS.