Hi Gordon, thanks for your comments.
Great minds run together, I ran some experiments this morning with the latest ESP32 dev module and the new Arduino IDE 2.o beta. The latest gen CHXXX USB serial interface does rip, and the serial programming performance is very good.
My only motivation for using Espruino on the ESP32, was consistency with my other code examples. I am working on some education materials, and am looking at some gentle, progressive code snippets to get familiar with the "big ideas" in low power BLE.
I'm getting a lot of inspiration from your recent YouTube videos on the subject.
I really like how you show the evolution of a generic BLE serial console, to a unique custom characteristic of your design, and then hit the Android Nordic nRF connect console to demonstrate manually stuffing a bit in the "register" to activate the servo. That seems like the learning trajectory best to follow.