> Gecko doesn't have a WebView implementation (GeckoView is not a WebView implementation), so it has to be used alongside the Chromium-based WebView rather than instead of Chromium, which means having the remote attack surface of two separate browser engines instead of only one. Firefox/Gecko also bypass or cripple a fair bit of the upstream and GrapheneOS hardening work for apps. Worst of all, Firefox does not have internal sandboxing on Android.
> The sandbox has been gradually improving on the desktop but it isn't happening for their Android browser yet.
That's fair and true. I guess my issue with Firefox is that Google is obviously Google, and you know what to expect from a company like that. Mozilla is pretending to be an underdog while at the same time they are Google by proxy - aiming to bring more telemetry, more advertising, more AI and doing it with Google's money which they take partly so that Google can say they aren't a monopoly.
It's the sneaky ways that Firefox are Google that bother me. Above you said that they recently added a switch to disable AI - only after backlash (though I have to admit that the original blog post said there should be an option to disable it). I also dislike that they are focusing on AI and advertising instead of improving their browser, but that's their decision.
Graphene user here: Firefox is my standard browser because I like it but mostly because it runs ublock Origin (which again causes me to like it). Vanadium I use for social media sites so I'm not logged in to those on the primary browser.
On GrapheneOS they recommend Vanadium - a more secure Chromium fork - and specifically recommend against Firefox, but that's on mobile.