To actually do something with a board, it's good to know which pin does what. The Feather standard already defines the functions of some pins, but they can do so much more. So here is a pinout with the most useful pin functions documented:

Initially I tried to figure it all out from the datasheet, but I quickly noticed it's non-trivial. Some timers and some sercoms are used internally by CircuitPython, and some are not available in the version of the chip I'm using. So instead I decided to take a brute force approach, and wrote a simple program that just tries all the possible combinations.

However, when it came to PWM, I simply gave up. The number of combinations is huge, especially since order of creating the PWM outputs matters, so I'm simply just marking which pins can have PWM at all. It's up to the user to check if the particular combination of pins they want to use for PWM is viable. I simply can't think of a way to present this information clearly in a graphical way.