Safari 14 will add support for the WebExtensions API but alas, on MacOS only (where presumably you will never see AMP pages anyway). I have idly wondered if it

Safari 14 will add support for the WebExtensions API but alas, on MacOS only (where presumably you will never see AMP pages anyway). I have idly wondered if it's possible to use Safari content blockers to trick the page into redirecting to the real site by blocking certain JS bundles, but I would assume not.