About the only use case I still need Chrome for is for sites requiring experimental web APIs not supported by Firefox, such as Web USB or Web Bluetooth. Site compatibility for everything else, including very heavy web apps, is just fine.
History sync is encrypted, which is what made me switch over in the first place (Chrome deactivates history sync when activating end-to-end encryption – go figure…)
The only site I have compatibility issues with on desktop is MS Teams and even then it's only for voice/video calls, everything else works fine.
Firefox Android is a slightly less happy place. The password manager doesn't work very well (am moving away from the built-in one) and I can't log in on Amazon (which is important because I can't buy Kindle books in the app because of the Play Store).
This is why I don't use FF (although I'm on Linux). It's unusably slow for me. My experience is not the most common one (indicating that there's something about my ecosystem that FF hates), but I haven't been able to make FF work in any of the releases starting a couple of years back, I think.
I don't browse on my phone at all, so I won't be using FF there purely for that reason.
I don't doubt your experience, but it's clearly not universal.