I think the limiting issue has been I/O. The recent iPhone 15 has 10gbps usbc which might be close but RAW images are quite big - not sure and too lazy to do the math.
The form factor issue feels tractable - just have the housing that you slot your phone into be a cheap bit of molded plastic that adapts it to the thing you sell that contains the sensor, battery etc. That makes it a ~$50 part at most that you can support nearly every phone on. There’s also spring loaded designs (look at all the spring based universal car mounts). Now that even iPhones are usbc, this also standardized the I/O connector port which would have been harder/impossible to solve and a bigger obstacle. The SW support thing doesn’t seem real - the R&D cost for maintaining the camera OS with its own custom gui is going to be much more expensive than just hiring some mobile app developers. Form factor feel might be an issue (ie wright distribution / Feel in the hands) and that might be a real issue. Not sure but also feels solvable.
But the biggest issue is that computational photography in a mobile form factor just isn’t relevant to the space that these manufacturers are in. The creators will use tools like darkroom and newer generative AI tools to post process and the value add of computational photography isn’t relevant there. “Computational photography” techniques to help capture and set up shots might be but I’m not enough in the space to know whether or not there always doing that (eg automatically being able to capture back to back shots with different settings for later compositing, providing automatic tips on lighting, etc etc)