During 2018, Safari on iOS started to support a partial implementation of the Web App Manifest spec that is overriding the apple-mobile-web-app-capable meta tags and consequent other sub meta data. But not all the spec is implemented and there is no documentation about this. In fact, even in WebKit Feature Status, the feature is marked as In Development and not as Partially Supported.
Properties that are not supported, but should be easy to implement based on current technologies on iOS are:
Properties that are not supported, but should be easy to implement based on current technologies on iOS are:
display: minimal-ui and display: fullscreen
theme_color for the status bar color scheme
icons, probably with purpose="maskable"
orientation
related_applications and prefer_related_applications to replace the old apple-itunes-app meta tag
shortcuts from the App Shortcut spec