Basically subject. I'd like to switch us from regular Firefox to the ESR branch while keeping everyone's profiles intact. Ideally the only thing anyone would notice is that it updates less frequently.

• How is this best achieved?

• Can this be done at any time or do I have to wait for an FF-ESR major version bump (so it's less "behind" FF)?

In case it matters, we're on Ubuntu, a mix of 18.04 and 20.04 currently. We've been using the stock distro FF and would switch to the Ubuntu Mozilla Team's ESR PPA.

My Google-fu is weak at the moment, so apologies if it's officially documented somewhere. If so, a link would be appreciated.

102 just arrived in the Ubuntu ESR PPA.
Copying the profile directory from ~/.mozilla/firefox to ~/mozilla/firefox-esr and editing both profiles.ini and installs.ini to refer to that profile worked like a charm (coming from a Firefox version < 102).