Android is used more here in India. Personally I haven't even touched an Apple device till date because it's just hard to find except in Apple store or if you have very rich friends. So I had no idea.
There might be good reasons to do it from Apple’s point of view.
For example, if Apple allowed third-party browser engines, any vendor could offer a browser with a vulnerability. That browser could be abused to install apps through that vulnerability, including malicious ones.
I’m not implying that it’s ok for Apple to act like that. My point is that it’s consistent with their security model for iOS.
The real reason is that they want you to get your apps from the app store and that's it. They can't get paid when people install PWAs or sideload open source apps. Same reason for killing the headphone jack. Same reason for having a different shape magsafe for every generation of MacBook. To keep the suckers spending.
More like embedded WebViews.