Real firefox on Debian [SOLVED]

Does anyone know how to install real Firefox on the Debian distribution (not Iceweasel or Firefox ESR)?

Apparently, there is something called Debian sid with some extra packages. Anyway, instructions are at Basically,
adding a line to your /etc/apt/sources.list like this: deb sid main. Then you do a sudo apt update and sudo apt upgrade and then install.

This might not be such a good idea. Now I find that mesa/openGLES support appears to be broken, so maybe I have introduced an incompatibility into my dependency tree. The answer may be to avoid Debian if you want to use Firefox. Does anyone understand this better?