I've been running Firefox as my default browser on my phone since 2018 without webkit. Even other apps opens their links with geckoview. It started with FF Focus, shortly after FF Preview, then FF beta and since last year FF for Android.
Apple on the other hand..
Sources:
Sadly the only thing it's lacking. Saw a couple of years ago they were looking at different technologies to implement it client side for privacy reasons.
Before post edit:
While looking for the source i found this:
Firefox Tests Privacy-Friendly Web Page Translations
It's coming bby!