Bluefin.

No need. Use GhrapheneOS without Google services. It is like dumb phone with modern browser.

Brave. Good defaults out of the box unlike Firefox where you need to fiddle with bunch of flags.

Cross-platform apps and adblocking.

For now...

There is no extensions on FF for iOS, no adblocking. It's just Safari skin.

From what source do you install those apps?

Like trans stuff?

AdGuard / uBlock Origin.

Safari as a default, Brave as a backup.

Of course you can. I'm doing it for years now.