are you using with only one Coral USB dongle at the same time (plugged in the PN50 NUC) and get successful object or person identification with frigate? And why telegram? Is it connected to frigate only for notifications resulting from the identifications?
Yes, only one Coral dongle and it's handles all cameras perfectly. With some masks I rarely get any false positives and it is like 99% correct hit-rate.
Telegram is just a way to get a fast glance of an detection, so it sends me an image with what type of detection it was and the frame it found it in with detection frame around the object. This is handled via Home Assistant and some automation I've written. The results comes via mqtt to hass.