Try Floorp. It's folk of Firefox, just like Vivaldi/Edge in Chrome.
It supports switching the look and do things like this repository does.
It supports switching the look and do things like this repository does.
The irony being not only are they a fork, their initial feature set was from existing add-ons that they were just downloading/installing by default.
Anyway, after googling the issue, the running of that browser is a bit too amateur hour for me to rely on for something as sensitive as a web browser, even if they have reversed course on the decision.