Use a reverse proxy in a DMZ. You can use something like Bunkerweb + Crowdsec to give you a WAF and dynamic IP blocklist in front of your web service.

Can’t you map Alt-Tab to one of the back buttons? Or does that not work in desktop mode?

EDIT: Or if that doesn’t work through steam then is there gamepad software in KDE or the Software Centre that lets the desktop map gamepad buttons?

I’ve been running Home Assistant (HAOS) on Proxmox for years with no issues. It doesn’t need to be on bare metal. VMs work fine.

They collect them. And when they have enough they can trade them in for a large stuffed animal.