would be cool if you could plug an iPhone into a dock and be able to use Mac OS from it... keyboard, mouse, full display.
Canonical (ubuntu) tried this.. it didn't get far for some reason. I wish it did.
Canonical didn't have the resources. Neither did Motorola.
But Samsung is doing this now with some moderate success.
what’s the benefit over having a separate laptop with its own mouse keyboard and display?
the drawbacks are large - you lose ergonomic touchscreen access to your phone.
This is 100% what you can do today with a Galaxy S9/S10, https://www.linuxondex.com, plug in your phone to a USB-C dock and get a full ARM64 Ubuntu environment
This has been tried with other phones several times. An idea without a market - no one wants to plug in their phone to get a desktop computer.