Hello @shay
sorry, my bad. I incorrectly assumed you'd be using an M5GO2 bottom with your M5Core2 which exposes ports B and C.
You are correct, the only port directly available on M5Core2 is port A, which by default is used for I2C and not serial. So yes, I guess the easiest for you is to get an M5GO2 bottom.
Thanks
Felix