Using your smartphone as your computer is one of the most “tested as a consumer failure in the market” features ever. Many have tried, all failed miserably.
Convergence is cool on paper until nobody uses it because it makes no practical sense. Useful to give great tradeshow demos, and that’s it
I've never been this consumer, but I imagine the hangup is that by the time you've added a keyboard and display to your backpack, you could've just added a laptop instead at a similar weight/size, and while the separate laptop means foregoing the continuity of state, you gain the ability to start your "large mode" session by merely opening a hinge, which is less friction (literally and figuratively) than docking disparate components.
I sometimes bring my laptop "just in case" when going to a friend's place.
If I could just plug in my phone to their USB C monitor that is already connected to a mouse and keyboard that'd be amazing for quickly using YOUR device.
Why would anyone need this? Because I could have my ssh keys and some software on it - sure I could have a bootable USB drive and try to boot their desktop (or laptop?!) from it... but that seems more involved than being able to converge your phone.
It's just that nobody nailed the software side of it. Apple could but they just don't care. Linux tried and they will keep trying
This is pretty much exactly what you're looking for. A phone OS on the phone, plug it in, get a desktop OS on a desktop. It worked pretty well, even for the limited hardware at the time.
If a device supports Displayport Alternate Mode on USB-C, there are docks that work like how you're imagining. But I do agree, for a lot of devices the mobile OS just doesn't really have a great desktop experience.
I'm not sure about the current distinction between iOS and iPadOS (Apple seems to periodically decide that these are the same things or different things depending on mood), but plug a mouse, keyboard and monitor into a modern iPad and you have... a surprisingly okay desktop for many use cases.
