Great work and collection of information.
I would hope we also could discuss the limitations that I2C has when using the traditional Arduino Wire library. For example, I2C does not work as well when used on the SAMD ARM architecture chips such as the Nano 33 IoT.
In my experience I have been unable to use the Nano 33 IoT to participate as a Slave with either a Nano 33 IoT, or Nano V3, or SEED XAIO. However, it will function well as a Master with these same breakout boards.
Not sure why this behaves this way or if a solution exists.
Thanks much all for the feedback.