Yep, both major non-Safari Mobile browser are still using WebKit, which means, it's probably better to use Safari unless there are compelling features that break out of the walled garden.
Apple rescinded the "WebKit for every browser" requirement, but Chrome iOS with the Blink rendering engine will supposedly arrive this year (2025) and yet I don't think a similar FF Quantum for iOS will happen anytime soon.
I happened to have FF installed on an iPhone 13 Pro because it synced over from an iCloud backup but I never bothered to run it since I tried running on an iPhone 6S once-upon-a-time.
Apple rescinded the "WebKit for every browser" requirement, but Chrome iOS with the Blink rendering engine will supposedly arrive this year (2025) and yet I don't think a similar FF Quantum for iOS will happen anytime soon.
I happened to have FF installed on an iPhone 13 Pro because it synced over from an iCloud backup but I never bothered to run it since I tried running on an iPhone 6S once-upon-a-time.