1. I believe icecat is going to update pretty soon to version 68 to track with the latest esr, so perhaps in a week or so please check the main channel for an icecat version that should work with most, if not all, up to date extensions.
2. If I do get Firefox built and packaged then I’ll be more than happy to add it to the nonguix channel. Though I’m strongly considering just creating an unofficial icecat that keeps up with the latest version of Firefox like icecat on windows does. We’ll see what happens after these tears dry.
Icecat is really just a set of scripts to strip out branding from Firefox and packages it with gnu shit, though the gnuzilla project provides the esr version for convenience.