If it is really only a private server for your friends, and they are not completely computer illiterate, then a Wireguard VPN or similar seems like the safest option.

But generally speaking it isn’t that big of a deal to temporarily open a port and forward it to a game server if you want to play a round online.

A VPS is not really cost effective for that kind of usage. Maybe one with hourly billing like this: tierhive.com