Maker Pi RP2040 Available GP Pins

I am trying to maximize GP pin usage. Pins 1,3,5,17,26,27, and 28 work fine. But when I attempt to initialize the GPIO paired pins of these (0,2,4,6,7,16,26) with this code:
I get the error:
Can these pins be used and how are they initialized?
- CODE: SELECT_ALL_CODE
tp1 = digitalio.DigitalInOut(board.GP0)
I get the error:
- CODE: SELECT_ALL_CODE
ValueError: GP0 in use
Can these pins be used and how are they initialized?