On iOS/iPadOS _all_ browsers are using Safari's webkit engine to render. That goes for FF on iOS, that goes for Chrome on iOS - it's all webkit.
Re:Firefox 72.0
by dkdbejwi383 on Tuesday January 07, 2020 @10:18AM
(#21980678)
For me it's mainly about synced history, open tabs on various devices (phone, tablet, computer), shared preferences, etc. The rendering engine is secondary to that in my list of priorities.
I have Firefox in the dock on iPhone and it's really great but random links, e.g. via messaging, get opened by Safari first.