"Currently the Matrix user can NOT invite other Matrix user in a bridged Facebook room, so only someone with a Facebook account can participate to Facebook group conversations"
But the latest version of the Facebook bridge added support for relay mode. So now you can invite multiple matrix users in a bridged room.
It says in the readme:
But the latest version of the Facebook bridge added support for relay mode. So now you can invite multiple matrix users in a bridged room.
Release: https://github.com/mautrix/facebook/releases/tag/v0.3.3 Issue: https://github.com/mautrix/facebook/issues/13