Gets stuck on major websites. The extension support sounds extremely fishy: I could install uBlock Origin, but either they are violating the Apple AppStore rules, or the extensions aren't actually working (fake API, not really implemented).
You cannot ship a JavaScript runtime in the AppStore, so you cannot ship a browser that is not a safari WebView, so extensions like uBlock Origin cannot possibly run on an iOS browser.
So which is it? They cannot get away with violating the appstore terms. It must be a shim API that marks the extension as installed to some degree.