I've switched to Zen browser recently (I like it's spaces and folder structure to organize work on a daily basis, same as Arc). fFox nightly is not there yet but it's getting close with tabs on the left..
I've also made the move to Zen. I think Arc users will feel right at home there. It hasn't quite reached he same level of polish just yet but being in active development is a big plus.
On top of that, Zen can be personalized with CSS. As someone who spends a lot of time in the browser, it's been awesome to be able to tailor it to my needs.
https://docs.zen-browser.app/guides/live-editing
I’m hopeful for Zen, not just as a successor for Arc but as a Gecko-based browser that sweats the small details. I appreciate that Firefox exists but it’s got a number of rough edges that’ve seemingly been forgotten.
One thing I noticed shortly after when I initially switch Arc a couple years ago from Firefox, ads were more targeted at me and I definitely felt more tracked online. I started using Zen Browser at work because they blocked Arc for Windows (Zen blocked as well but I can run the Twilight build without being blocked :D) and the more I used it I just like it better than Arc in general and it was nice to be back to using Firefox again. When Arc went into maintenance mode it was just that last thing to finally get me to move off of it and over to Zen everywhere.
Arc is based on chromium I believe and that has manifest v3 which means poorer ad blocking afaiu. I won't touch any chromium implementation with a 10 foot pole because of this exact reason. Arc also does not allow you to export bookmarks natively. i had to use a 3p script to do it
Actually you can do it in chrome (having multiple profiles basically), but yeah nowhere as good as arc is, i'm using zen rn but still very sad for arc, I have some hopes they bring back arc to life (either directly or inside of Dia)
I think the one you replied to was referring the fact that Arc can have multiple windows (terminal) "attach" to same tab (tmux session), that has nothing to do with profile.