Firefox

Create Firefox launchers

Launch the Firefox profile manager:
$ firefox -ProfileManager

Launch a specific profile:
$ firefox -P "ProfileName"

There's an extension made by Mozilla themselves, Multi-Account Containers, which could be useful for your needs:
https://github.com/mozilla/multi-account-containers

I guess you could say it works as a "profile-lite" feature.

I had no idea you could do that via about:config 😅 I would always either disable "Use the selected profile ..." or launch it with firefox -P --no-remote as suggested.

FYI after years of having several profiles for different activities, I settled down on Multi-account containers and have been quite happy with it. I even wrote a little blogpost about my experience sometime ago - you might find it useful.

You can use Profile Switcher for Firefox extension

https://github.com/null-dev/firefox-profile-switcher

https://addons.mozilla.org/en-US/firefox/addon/profile-switcher/

It doesn't work the same way as Chrome, as a warning though. If you open links from other applications, it will only open in the first instance of Firefox.

Also the profile manager can be used with a shortcut: https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles#w_start-the-profile-manager-when-firefox-is-closed