Apple declined to implement 16 Web APIs in Safari due to privacy concerns

I assume this means that APIs such as https://developer.apple.com/documentation/uikit/uidevice/162... are not available for their instant apps (the so called "Clips") ?

This is not related to developing App Clips, just Safari. (Aside -not sure why you're using such a derisive tone with that 'so called' stuff - companies name technologies for many good reasons, so just go ahead and use the name.)