Mozilla is unhappy because the use of browser engines other than WebKit will be restricted to the EU, forcing them to develop two different apps.
For an independent browser like Firefox, managing two browsers is not easy, so it can be forgiven that this could be seen as almost harassment.
Also, the fact that the use of browser engines other than WebKit is limited to iOS means that the use of WebKit is still forced on iPadOS, which also increases the effort for Mozilla.
Ditto! No Google needed, and Facebook apps are prohibited on my phone. I can even get banking apps working with a bit of Magisk, working in Zygisk domain with a deny list hiding it from the apps. Apparently proper SafetyNet checks aren’t that common anymore.
For browsers, I’d recommend Mull and Mulch. Mull is a privacy fork of Firefox, Mulch is a hardened version of Android System Webview (the backend browser that lots of apps use). Both come pre-installed with DivestOS.