Should be "go android". All iOS browsers sadly are just WebView shells.
"Apple Considering Dropping Requirement for iPhone Web Browsers to Use WebKit"
https://www.macrumors.com/2022/12/14/apple-considering-non-w...
The parent poster is talking about system webviews. They're used when any app wants to show web content embedded inside their apps, and yeah there's no Firefox option for those.
If you don't care about any of the extra functionality, you can configure it to always open your preferred browser and convert Custom Tabs intents to regular ones. No root access required.