Thanks giuliomoro, I have the BelaMini and I'm using C++. A simple example is that input on the ESP32 would cause a sound to play on the BelaMini. Data will flow back to the ESP32, but that latency is not as important in that direction. I suppose I could use 2 I2C to get full duplex. Overall the path looks like this:
ESP32 <--- ESP-NOW ---> ESP32 <-- SPI/I2C ---> BelaMini
How about overall latency from SPI/I2C to the C++ interface? Any ideas of the difference there? I'm guessing the software stack is also a factor?
And for the complexity of the libraries, and ideas on which is easier? I saw SPI libraries mentioned in the forums and some code checked into git. Is there a major difference in complexity from C++?