Other models are coming but the pivot is a common part to all bikes, accessible for charging and for GPS/GSM signals. 

Moreover, it’s a solid base to mount a tracker that will be difficult to remove.

There are few possibilities on a bike.

The seat flies, the seat post is not pierced, the handlebars do not have the same diameter, etc.

The pivot is therefore a strategic choice for a first model. It is also a very complicated place, because surrounded by metal parts, it requires a solid expertise to operate GSM antennas in such a small space.