Main Firefox/ESR profile window and another instance with different profile/plugins.
Second profile can be done under Linux by copying Firefox launcher menu entry making same new one and modifying command line to have -p parameter. For example:
(right FF path discovered using command "whereis firefox")/usr/lib/firefox/firefox %u -p -no-remote
Now after launching it i can see the profile chooser menu.
Selecting my secondary profile it was complaining it can not use it since i am using different (older?) version of Firefox (actually Firefox ESR).
And prompted to quit or make new profile.
SOLUTION:
List profiles:change particular profile file:ls -lt /home/$(whoami)/.mozilla/firefox/
Prefix line "LastVersion=..." by # character (commenting out). Savenano /home/$(whoami)/.mozilla/firefox/myprofilehere.default-release/compatibility.ini
Now it launched profile anyway and i see plugins was active and it restored tabs.
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