The garble your getting is gps data just wrong. Check that the baud rate set matches your device. That’s normally the main cause by default the raspberry pi is set to 11250 or something like that. My script sets the baudrate to 9600 just for the script.
Try this command
stty -F /dev/ttyUSB0
Then
stty -F /dev/ttyUSB0 to make sure it’s set of not run the previous command again
Then sudo cat /dev/ttyUSB0 9600
@wil I don’t have any of those programmers so no worries, I totally understood that it was a prototype so that means something may not work and I laughed at the text, found it quite funny