are these "default" settings for the project IO config accurate for MPW-2/3? In particular, will something like UART RX or GPIO input work with the default settings after a reset, or do IOs need to be manually configured for the management core to have GPIO-input as well

The default settings are now required to be set by the user before submission. However, I think for MPW-2 and -3, this was optional, and if the user did not create a user_defines.v file, then the one in the caravel repository would be used. That one sets all GPIO to management-controlled input. So the UART Rx should work on startup, as should the GPIOs 5-37 (as inputs).

ah great! that should make it easier to push the rest of the IO configs in through the serial port