Wasn't there a proposal to expose native functionality in browsers on iOS and Android? If that were to be finished it could make things like this and react native less necessary.
Why would Apple ever implement that? They’ve made their point of view on preferring native development (and being very cautious about what’s exposed to the browser) very clear.
For me one of the showstopper for webapps on iOS was that there is no immediate, synchronous way to communicate data between the native part and the visualisation part. Since the only way is to communicate via messages which are painfully slow.