I've been using the Firefox docker container through the gluetun docker container (runs great with proton and mullvad) and it's been really great.
To me it's kind of like a less restricted tor browser, for when you need something stronger in terms of speed or IP blocking. And maybe something more persistent.
And it always stays open even when you close your connection.
Some of my use cases are:
Anonymously downloading larger files through the clearnet.
Anonymous ChatGPT usage.
Manually looking for torrent magnet links (though I usually do that with the tor browser)