My ‘23 Emonda has this on the inside of the non drive line side of the chainstay.

I believe a spot to install a Bontrager sensor, seems to be combination of speed and cadence. Is this actually a speed sensor ?, I would think a sensor of any kind would need to sense wheel revolutions. Cadence I could see if it had a corresponding shoe sensor, How exactly does this work, the Trek info is somewhat vague.