Possible to determine which teensy board from bootloader?


I have a custom program that knocks Teensy 4.1 into bootloader mode then programs it from a hex file.

Is there a way to detect which teensy I am connected to while in the bootloader?
There is a chance people will try to use it to program a teensy 4.0 which I don't want to happen.

I have seen the teensy loader CLI source code and a few bits of (out of date looking?) info on the website here;

Is there no other way to just ask what the CPU is or anything like that?