Arkenfox <https://github.com/arkenfox/user.js> is a community maintained user.js file used for browser hardening.

Proposing to implement it's configuration in GNU Guix's IceCat mainly:
- geo.provider.network.uri (it's pinging google servers currently)
- Actual disabling of WebRTC
- Clearing on re-start (privacy.clearOnShutdown.*)
- toolkit.telemetry.enable = false instead of forced true
- etc..

Additional configuration should be defined in guix-home with sane default so that the browser can be a sufficient replacement for Tor Browser Bundle.