What did I learn?

Alas, not much. The same code on the ESP32 works with both throttle bodies, cycling them through the same 'script' of gradual and rapid transitions from one blade angle to another.

The voltages and ADC signals from the two are not identical, but they are quite similar.

The NW102 can draw more power, but not a lot more. 

The NW102's rest position looks like it would allow more airflow than the LS2 throttle body's rest position, so that's something to look into more. There's a set-screw on the side of the TB that might adjust this, but it really does not want to turn. At some point I may need to disassemble it and see if it really is an idle adjustment, or if it's just holding something in place.

The NW102 opens past 100%, to the point where the blade appears to begin restricting airflow again. I've read that gold-blade LS2 throttle bodies can be made to work by (swapping sensor wires and) tuning the PCM to allow only 90% throttle opening, so that might be a factor here as well.

What are the next steps?

Put the NW102 back into my car and get more information about the failure mode.

My car is on jack stands right now with a broken engine, so I may not be able to learn much, but it's worth a try. 

Real progress might need to wait until the new engine shows up - which was supposed to be a month ago, so I can't make any predictions.