

Copying the profile folder should do it
You should also copy profiles.ini (which indicates the path of the working/available profiles)
I see, thank you. That seems to be what I found out when I researched this as well.
If they are too behind the version that the profile is from then there might be “forwards compatibility” issues
Good point. I’m still using Mozilla’s firefox, but am planning to try out Zen Browser, or go with Waterfox if Zen’s Arc Browser style isn’t up to my needs. For example, I’m very happy with the sideberry add-on on firefox.
Pre buy out, Opera was kind of moving towards what Proton is doing now.
Now Vivaldi sets to continue that trajectory.
It’s weird that Mozilla didn’t. If they do it now they’ll look like copycats, and they’ve burnt a lot of supporters with their TOS boogaloo it would take a lot from them to claw back some of those supporters