iOS debuted a feature called “App Clips” awhile ago (2020?) that would be perfect for this. Most phones have an NFC reader as well so should work with Android

iOS debuted a feature called “App Clips” awhile ago (2020?) that would be perfect for this. Most phones have an NFC reader as well so should work with Android too. Similar concept: 1) person taps phone against “door bell” 2) sends notification to user(s) 3) optionally, send “selfie” IIRC, app clips needed to be very small in size. So something like this could work, even in low bandwidth situations (ie, poor signal strength)