One of us suggested AirDrop and we sent dozens of photos and videos between us within a few minutes time. Maybe this seemed more impressive to me, after several days of suffering a terrible internet connection. It definitely stood out for me as being one of those moments where technology can make things easier and magical.

I do wonder if there are patents on this, and if that has prevented other devices from adopting this kind of protocol?

WiFi has always had AdHoc mode which enables two devices to directly communicate like they were on the same Ethernet link, and I've used it a few times for a similar use-case to yours. It seems AirDrop is just a layer on top of that which facilitates the configuration required, but otherwise it would probably not be too difficult to "roll your own" similar app.

Aren’t many devices limited to one WiFi network (whether ad-hoc or infrastructure) at once? That would mean many devices couldn’t do this without breaking normal WiFi.

Miracast is another example of this - In most cases you can remain connected to your main network connection via Wi-Fi but also use Wi-Fi direct to run a casting session.

Some of the older devices don’t support it, or people aren’t signed into iCloud or have a problem with their sign-in.

Even a basic Android app would do and I think it's perfectly fine if one can have an iMessage account on other platforms iff they have at least one Apple product with "Messages" app on it - an iPad, a Mac, or an iPhone etc.

It's a pretty good messaging service but almost useless to me (and I am sure to a lot of people) because very few among my friends have iPhones but a hell lot of them have Macs - like really a lot!

[1] https://play.google.com/store/apps/details?id=com.apple.andr...