During some recent development on Funtoo Raspberry Pi coffnix and borisp and myself explored cross compiling Firefox using fchroot and making a Portage binpkg for it here: https://area31.host.funtoo.org/funtoo-raspi4/

The current version of source compiled firefox is only 99.0.1. This is a request to add the latest Gentoo upstream here https://gitweb.gentoo.org/repo/gentoo.git/tree/www-client/firefox/firefox-101.0.ebuild

If Gentoo's upstream ebuild is not acceptable then we can adapt Funtoo's current firefox ebuild to the latest version.

This is an interim step to get the latest firefox available to Funtoo RPi/arm64 users. It would eventually be nice to have www-client/firefox complete autogenned.