This might help, some things may have changed Pico Graphics wise since then.
Trying to run dual independent displays on a Pi PICO - Support - Pimoroni Buccaneers
EDIT: I think this may be the way to go, these days.
pimoroni-pico/micropython/modules/picographics at main · pimoroni/pimoroni-pico (github.com)
pimoroni-pico/micropython/modules/picographics at main · pimoroni/pimoroni-pico (github.com)