BACKGROUND
CURRENT SITUATION
Right now, you can install Firefox and load a CSS theme to make it look like a native GNOME App.
Source: https://github.com/rafaelmardojai/firefox-gnome-theme
While it looks really nice, it would be nicer to have a native GTK4 Firefox Browser with responsive design because there's also a GNOME-based phone environment called PHOSH.
SOLUTION
I propose a new browser called: Firefox-GTK. A collaborative project between Mozilla and the GNOME Foundation. It would be the same Firefox we love and enjoy, but tailored for the GNOME Desktop. If Firefox and GNOME Web had a baby, it would be Firefox-GTK.
WIIFM
CONCLUSION
I am 100% positive that GNOME will become a real contender against Apple and Google in the mobile space. When Mozilla released Firefox OS, the timing wasn't right. But now we have powerful PWAs, and Mozilla doesn't have to reinvent the wheel. We already have a plethora of Linux Operating Systems that work on phones (mostly the PinePhone), We have a Graphical Environment for phones called PHOSH, We have Powerfull PWAs, and many native GNOME Apps. All we need is a powerful web browser to create the perfect privacy-focused ecosystem.
A preview of what PHOSH is capable of right now.
Note: There's already a request on Bugzilla about porting Firefox to GTK. Report # 1701123. Furthermore, This topic is also mainstream on Reddit.