@Roger-Sinasohn OK. Now I see that you want to use a special momentary (ON)-OFF-(ON) version of the standard SPDT switch.
It has a third switching position in the centre which is off and returns to the central off position when released.
About the 8th GPIO:
Omega2(+)'s U-Boot set GPIO11 to Output and High (this is a "secret" hack of Onion guys ;).
With a fast-gpio set-input 11 command you will get that highly requested 8th GPIO Input - but in this case
Maybe I'll write "a few" words about that debouncing circuit... later.