This has gotten some attention, especially about a week ago, but I really hope more people will continue to try it and, if interested, support it. It is Firefox, but heavily modified to please a different audience that prefers a slightly different UI than Firefox. It has some of the appeal of Arc, Vivaldi, and the Sidebery extension.
In my view, it is very promising, and all competition in this space is good. Here it is on Github, also.
The profile switching is just that of Firefox, but with a button that makes it a bit more accessible. And there is the concept of workspaces within a given profile, but I haven’t quite figured out how to set it up best for my workflow yet.