Yes, as a previous-gen iPad Pro owner, the biggest regret with it is, that I cannot run even some very basic Unix programs on this great hardware. A more open iPad - even if the whole Unix userland would be contained to a sandbox - would be a dream.
It seems Apple has some really good profit margins on it's hardware. So, in theory nothing is stopping System76 or a new competitor from introducing high quality iPad-like Unix systems.
Except that System76 or who ever would need to be capable of building iPad-like hardware. I really don‘t see that, at least not a a competitive price point.