There have been some failed attempts, most famously the Ubuntu phone, and a few Kickstarter projects, as well as Microsoft trying to do an OS to fit them all. But none of them have been much serious.
With the current technology, an Android phone could be built such that when connected through HDMI it launched a Linux desktop such as Debian (like Maru OS, but it is a hobbyist project). Apple could do the same with iOS/Mac.
Furthermore, if foldable phones were industry standard (not there yet, I know), the phone could double up as a tablet/laptop.
Probably there is no demand for such a device, and we can argue that it's better to have a device specifically designed for one purpose (communicating, working or gaming). However, I believe that the failed/current attempts were not serious enough, and if a big OEM wanted, an excellent all-in-one device could be shipped. I would be the first customer, waiting the whole night like some Apple customers do. Also, I'm kinda tired of taking care of 3-4 devices with their own update cycles, cables, and so on.
