Incidentally, I'm not sure about Squeak as the main user-facing bit, either. I love the idea of having a handheld, battery-powered, internet connected Smalltalk machine; but Squeak's UI is currently very desktop-focussed, and single-host-window-focussed, at that. (I'm working on that latter elsewhere [1].) Squeak's flexibility means it doesn't have to stay that way, and experimenting with alternatives is easy, making it maybe a good environment to prototype alternative phone UIs. Whichever way you slice it, it's a lot of work, of course.

[1] https://squeaksource.com/X11.html