All great changes! I've been using Floorp to have vertical tabs, but I'd gladly switch back to Firefox when its implemented. Profiles have always been a great feature, but had a bad user experience, glad to see its being improved.
Really interested in the local AI. Firefox has been doing interesting work with that recently.
I've tried a few extensions, but they haven't felt as integrated as the one's in Floorp, due to firefox limitations. The main reason I want vertical tabs is to save vertical screen space by removing the horizontal tab bar, which can be done with userchrome.css, but thats inconvenient to do on multiple devices. I appreciate the recommendation though, I haven't used that one and it looks very powerful.