Why will they be blocking the IMEI?

Waydroid emulates Android (in this case AndroidTV) on Linux, allowing you to run Android apps inside your Linux-based OS.

LibreELEC (just enough OS for Kodi) on Raspberry Pi supports CEC. Does that count as a PC?

As long as it isn’t internet connected, it shouldn’t happen - unless it’s programmed to automatically connect to any nearby unprotected WiFi to fetch updates…

If it’s not a Pixel, it’s currently not possible. If you don’t need the security features of GrapheneOS, you could look into LineageOS on a wider range of supported devices.