Thanks for mentioning this. Somehow I've searched for something like this before and couldn't find it.
That didn't stop me from using Firefox tough. I just have my first bookmark in the toolbar point to "about: profiles" and use this page to launch new profile instances, create new ones etc.
I use profiles extensively and would love to know which extension you are using. Containers cover most of my sandboxing needs for private browsing, but I prefer to have a separate Firefox profile for business accounts/apps.
The thing that has me stuck on Chrome is that it doesn’t automatically open the profile you last had focus of. For example, if I have last touched my personal profile I don’t want to open a new link from Slack in my work profile.
Having the ability to only default to one really sucks.