strycore Debian Testing and Stable have had Firefox-ESR for nearly 4-6 months now...

https://packages.qa.debian.org/f/firefox-esr.html

the iceweasel package has for the longest time been a meta package which pulls in FF-ESR.

I've running Debian testing on my laptop and work desktop for the last +2 years.

the newsie bit is that finally icedove (yes Venn somebody actually use that thanks to corp's use of Exchange >_< ) is getting the same treatment...
Debian's QA modifications and repackaging are now been allowed by the Mozilla foundation, which due to some gray area in the MPL license about
re-distributing complied from source copies for FF and TB that could be a violation on Mozilla Trademark finally has been sorted out.

Pedro if you re-watch LWDW-GPLDecline, your second try on my family-name was close, the Danish language is a bitch for non-natives.