From what Apple say for Content Blocker API on iOS, I suspect that they really avoid to implement those API.
> In addition to blocking unwanted content, a Content Blocker extension protects privacy. For example, the extension doesn’t have access to users’ browsing activity and it can’t report activity to your app.
> In addition to blocking unwanted content, a Content Blocker extension protects privacy. For example, the extension doesn’t have access to users’ browsing activity and it can’t report activity to your app.
https://developer.apple.com/library/archive/documentation/Ge...