I only realized after creating this thing: You can rotate the mount, just press the arm in... (So the thing is useless unless your phone is too long.)
I modified DarkTreader's adapter, so the skycontroller can hold a smartphone with this.
It was a test version but fits perfectly, so I shared it.
Fits my honor 9 lite with case perfectly.
You can put the phone to the top or bottom, whichever is your preference. For beginners, the top might be better so you can see your hand and the sticks, too.
I printed it with 20% infill and supports for the overhang, but it is not neccessary. I printed the tablet version without that, and it came out fine.