This cheek pistol concept is a quite valid, in my estimation, especially with BATFEmen wanting to forbid extended pistol braces, but being left-eye-dominant, and with the ejection port of most weapons being on the right side, I believe that I would have to completely close my dominant left eye, to enable this to work when firing from my right cheek. Perhaps, the optic could be mounted, on an offset mount, to the left, to enable firing from the left cheek, with both eyes open, and the cases ejected at enough of a downward angle, to enable the ejected brass to clear? Yes, the substantial offset would need to be sorted-out, and I am not sure it would be workable. And, yes, an offset optic increases the bulk of the weapon, which means a wider amount of bag space, for toting the weapon. May not be worth the fuss, for this left-eyed guy.
Kel-Tec? Hmm. I have seen some very interesting B&T pistols, at an LGS, that might be good cheek pistols. One of the Demonstrated Concept videos shows a B&T TP9 being used.
https://www.youtube.com/watch?v=yHkGyjsq7hQ