You could potentially run a backup site or a different lemmy instance, but that requires people possibly knowing your real IP and port forwarding (unless you use a VPN or port tunnel), technical knowhow, and constant uptime. If you don't mind ruining the PC, you could also test software / cracks on there. (Turn off your internet if you're planning on doing this.)

Honestly, the best way you can help is contributing to the wiki and helping people out in Divolt and on here. No extra computer needed.