[chx]

I am not so surprised, the challenges for connecting a phone to a camera quick and reliably is formidable. You need a connection capable of transferring a several hundreds megabit file in a reasonable time (a RAW is like 40MB). Bluetooth just won't cut it. Of course, in theory WiFi Direct would do it but then Apple obviously does something else. Wired connection, unless you want to fiddle with the connector would require magnetic connectors and at least today there are no USB C magnetic cables which would or rather could adhere to the specification. It's been three years since https://twitter.com/USBCGuy/status/1186718432932159488 and there's still nothing.

And of course this is just the electronics, then you'd need to work something out mechanically. It needs to attach safely and quickly but also detach when needed. It's instructive how most quality phone cases are not universal rather there's a separate one for each model.