Perhaps the easiest technical solution would be a cheap phone and a plan that allows tethering? That gets it off your network and your personal public IP for $NOTMUCH/month.

It's still possible that your employer might use their laptop's WiFi, Bluetooth, microphone or camera to do various nefarious things, but ... unless you're genuinely worried about nation-state level shenanigans, I think that'd be excessively excessively paranoid.

Either way: distrusting your employer this much might indicate that it's time for a new job?