The sites are probably using data from the railroads in some form of cellular based GPS tracking for their systems. asm.transitdocs.com is one for Amtrak in the US. Probably used by the RR to determine schedule changes on the fly.
The data wouldn’t be coming from PTC, since that info has been available before the PTC network was even in place. I would guess PTC does relay position info though as a way of tracking in the system, since the purpose of PTC is speed enforcement based on the train’s location.
I wouldn’t get your hopes up too much.
Mike