For Win 10, I set this up a while ago so my memory is a bit fuzzy but the key was the `taskbar.grouping.useprofile true` setting. I think after that's set Firefox and Windows did some AUMID shenanigans on profile launch.
I just made a new profile as a test and this is what I did:
...firefox.exe" -P -> create a new profile (ie. "newprofilename")
about:config set `taskbar.grouping.useprofile = true` (when I originally did this for many profiles I believe I copied prefs.js that already had it set)
close and reopen that profile instance. I used ...firefox.exe" -P "newprofilename" but any method of launching the profile should work. It should now be in a separate taskbar group.
Pin that new group to taskbar. Also modify its shortcut target to add -P "newprofilename"
Now you're done.
Normally I also renamed the pinned shortcut to something sane and then I changed the icon. I took the normal Firefox icon (I think w/ GIMP) and just messed with the colors via saturation or something so it was easy to tell the difference. I remember changing the shortcut icon had some headache but I sadly didn't write notes.
Also, I didn't set grouping.useprofile on all my profiles, just the profiles I wanted separately pinned on my taskbar. My default profile is pinned normally without grouping.useprofile set.
I just made a new profile as a test and this is what I did:
Normally I also renamed the pinned shortcut to something sane and then I changed the icon. I took the normal Firefox icon (I think w/ GIMP) and just messed with the colors via saturation or something so it was easy to tell the difference. I remember changing the shortcut icon had some headache but I sadly didn't write notes.Also, I didn't set grouping.useprofile on all my profiles, just the profiles I wanted separately pinned on my taskbar. My default profile is pinned normally without grouping.useprofile set.