There are people literally printing out the entire internet. I’m pretty sure ANYTHING connected to it can be found if you try hard enough.
For most home users, who have a firewall/NAT router, no. The Photon’s connection to the Particle cloud is out, to the cloud, even though data goes both ways once connected. Shodan looks in, looking for exposed ports. Since you don’t have to reconfigure your router to expose inbound ports to use the Photon, no, it’s not trackable that way.
How could it be trackable?