Thanks - I'm not new to the forums. I teach Arduino classes both online and in person and I'm very familiar with how infuriating it is when someone says "it's not working" as if you can magically fix their problem without seeing either their circuit or their code.
In this case, I'm not looking for someone to help debug my hardware/code, which I've verified is working as I mentioned with the oscilloscope output. I'm just looking for any broad/general pointers as to whether anyone has gotten this type/class of project to work (basic haptic feedback demo with cheap ultrasonic transducers).