Lets start with a browser based application that struggles with basic IOS capabilities. Not entirely a web app’s fault, but dealing with badges and push notifications will most certainly be a better experience in a native app.
I admit that I am not saddened by this hurdle. The moment that becomes a thing, further enshitification will ensue with every web site trying to drop and icon and start pushing messages.
“Closer to metal”? Not sure you are wrong to ask if there is a line given SwiftUI. That is some very high abstraction.