I'm not that optimistic that Mozilla is capable of building a good iOS browser. It's been a few months since I last used it, but the issues of Firefox on iPadOS were not because of the engine. Tabs would frequently lose order, closing a tab would close some other tab, broken keyboard shortcuts, cursor/selection issues in the address bar, random non-responsiveness and just janky UI. The issues were so obvious that it felt like it was built without any QA process, so I resorted to using Safari most of the time, which worked perfectly.
Firefox Focus on Android works much better, but it's also a simpler browser. I haven't used the full Firefox on Android, so can't comment on that.
Firefox Focus on Android works much better, but it's also a simpler browser. I haven't used the full Firefox on Android, so can't comment on that.