> In iOS and iPadOS 16.4 beta 1, third-party browsers can now offer their users the ability to add websites and web apps to the Home Screen from the Share menu.
If it's available for webkit-based third-party browsers now, it seems like it would probably be available for non-webkit browsers as well. Maybe not, but at least the door is open for it. It would be hard to justify the limitation.
At this moment of time, there aren’t any non-WebKit browsers available in the App Store, so “third-party browsers” in this context means “WebKit browsers”.
If it's available for webkit-based third-party browsers now, it seems like it would probably be available for non-webkit browsers as well. Maybe not, but at least the door is open for it. It would be hard to justify the limitation.