They are currently closed source like Brave for now but it’s a relatively new browser and still technically open beta (I’m on 0.99.124.4.1).

They say they are working on going open source. However their Github seems to currently get infrequent updates.

For iOS there is the Orion Browser. Its a privacy based fork of Safari for iOS and macOS, with built in ad-block, anti-fingerprinting, and supports background and PiP youtube. I use it as my default browser on iOS and Mac.

Its built on webkit, just like Firefox on iOS, but supports both Firefox and Chrome extensions. And their CEO isn’t a crypto shill or anti-lgbtq.