Leader-only images have this bug currently (fixed in the next release): you’ll have to use the manual fix here: Leader only image bug - HardwarePWM not found - #3 by CamDavidsonPilon
I suspect the next release will come early this week with the fix (and other changes)
pio update firmware
I don’t expect this to work, since the firmware lives on the HAT (plus you need the internet to pull) - what you probably are interested in is pio update app or pio update ui. However, if you want to the latest development versions, you can use pio update app -b develop and pio update ui -b develop` (both these require internet connection).