Creating Animated PNGs (APNG) with Shotcut

Just in case someone else wants to make Discord stickers that frustratingly MUST BE APNGs, here's the preset that I used to get Shotcut (video editing software) to do it:

audio_off=1
f=apng
an=1
vcodec=apng
width=320
height=320
aspect=1
progressive=1
frame_rate_num=3000000
frame_rate_den=1000000
threads=9

Essentially the only lever you can pull to reduce filesize (stickers must be < 512KB) is framerate. No quality options in the encoder do anything with APNG encoding.

Important: The filename must end in .png, NOT .apng.