That's why I wrote "virtually". Others suggested virtualization, which I think would be a good tradeoff that doesn't require usability changes to the underlying

That's why I wrote "virtually". Others suggested virtualization, which I think would be a good tradeoff that doesn't require usability changes to the underlying OS (and would finally put the processor to good use). Other than that, the inability to code on iOS is due to artificial gatekeeping by Apple, not due to design decisions. There are many ways coding (and probably other types of apps!) on iOS would be possible, if it wasn't for Apple.