I can't find a definitive statement about which pins on the GIGA support PWM.
The datasheet says:
The board provides 76 digital inputs/outputs (12 with PWM capability)
However, from the screen printing on the header sockets it looks like:
2 to 13 and 22 to 53.
When I try a pin not in these ranges, such as 14, the red LED flashes what looks like morse code, and the board hangs up and has to be reset with a double press on RST. Is this intentional? If so, it would be good to document it.
Note that this has been discussed on a previous thread without a resolution:
https://forum.arduino.cc/t/why-cant-i-pwm-the-pin-13-led-on-the-arduino-giga-wifi/1120299
Thanks - that's useful. That explains the red LED flashing morse code.
However, it repeats the statement:
The GIGA R1 has 12 PWM capable pins, the PWM capable pins are 2-12.
However, this omits 13 and 22 to 53 marked on the header sockets. I haven't tested all of these, but 13 definitely works, 22 doesn't, and 53 does.
Did you see the table of pin functionality headed Pins
Did you see the screen printing on the header sockets 
No, I didn't
You seem to have worked out which pin's provide PWM by experimenting
Sorry I wasn't clear. This is what I was referring to:
Just Dropping a link for reference. https://docs.arduino.cc/resources/pinouts/ABX00063-full-pinout.pdf
Look in the Advanced section for far more details on pin assignments.
