> palemoon and waterfox seem to be running just fine.
GNU/Hurd is also a very interesting alternative OS, the design is a lot more elegant than GNU/Linux, it's still under active development and it has a surprising number of active users.
It's still a very bad idea to build the foundation of your tech stack on it.
Thunderbird also works.
I happen to own a brwoser extension and have both chromium and Firefox extensions. I kinda know myself.