Thanks for the pointer. I found that, but I don’t know what a DT expansion board is. The fact that working ports change from configuration to configuration also prompted me to doubt that whatever approach that would work for the standard configurations (A06, rpi CM4, etc) would work in this case, thus my question.
EDIT Right, DT=DevTerm, meaning the DevTerm EXT board. I suppose I could reimplement a debug board expansion card based on the schematic. In any case, GPIO 32 and 33 goes directly to UART.