Absolutely. There are many many ways to do it, however. I make some suggestions here: Share one Blinkt! with multiple RPi3
I think i2c to a host microcontroller, or host Pi, is possibly your best bet, but you could do crazy things like assign 8 pins to be an 8bit (0-255) output and read that.
The real trick is how you read the GPIO pins and display the result on the pHAT of course!