Your fingers are doing double-duty pushing buttons and yet also holding the phone/keyboard combo without pushing buttons. Even this design has that problem to some extent and it's got a lot more room to hold the phone.
6 fingers might work. I'm holding my phone in landscape here with my thumb and pinky. I've got three fingers in the back on each side I could use. I think I could just about get two layers of buttons in for each finger without too much discomfort, but my ring fingers aren't too happy about shifting down to try to reach a fourth there. (And while every other aspect of the skillset has long since decayed, I did play piano for many years and I still retain those basic muscle skills; if mine are complaining there's a lot of people who straight up won't be able to do it.)
12 still leaves you with chording or arpeggiating or something very, very non-standard, though.
I don't think you could hold it like that for very long. Just in the time it took me to type out my brief experiences on my real physical keyboard afterwards my pinkies are already tingling just a touch. Not a good sign.
An interesting experiment to see if the back of the phone is useful for anything, though. Certainly worth some more thought and experimentation. Phones would be so much more useful if they had something like keyboard speeds available in our pockets.
6 fingers might work. I'm holding my phone in landscape here with my thumb and pinky. I've got three fingers in the back on each side I could use. I think I could just about get two layers of buttons in for each finger without too much discomfort, but my ring fingers aren't too happy about shifting down to try to reach a fourth there. (And while every other aspect of the skillset has long since decayed, I did play piano for many years and I still retain those basic muscle skills; if mine are complaining there's a lot of people who straight up won't be able to do it.)
12 still leaves you with chording or arpeggiating or something very, very non-standard, though.
I don't think you could hold it like that for very long. Just in the time it took me to type out my brief experiences on my real physical keyboard afterwards my pinkies are already tingling just a touch. Not a good sign.
An interesting experiment to see if the back of the phone is useful for anything, though. Certainly worth some more thought and experimentation. Phones would be so much more useful if they had something like keyboard speeds available in our pockets.