This is excellent news. This is one of the biggest features that I've wanted out of Firefox for years, and one of the reasons I've kept Chromium as a secondary browser all this time.

I do remember seeing a community-made GitHub project that added a profile switcher to Firefox, which looked pretty good, but it also required installing an executable somewhere on the system, which I'm not exactly keen on.

I think Zen Browser has a built-in profile switcher, but it also changes a bunch of core UI elements... I just want Firefox with a profile switcher, lol.