Paul
Thanks for your help it is much appreciated, and helps tremendously.
For the prototype I can use less pins to make it easier to access pins that are easier to get to.
As for using mux or extenders, for my application this would not be fast...
Looking at a project that needs 100 dedicated GPIOs to monitor state changes. They would be set as pull-up interrupts, and then a few other GPIOs for control/comms with a host Teensy (code already written and working).
MIMXRT1062DVJ6 datasheet...