Here’s the current list:
jpg
jpeg
mp3
m4a
m4v
mov
mp4
png
gif
webp
svg
pdf
ttf
woff
woff2
eot
xml
txt
text
js
json
css
html
htm
md
zip
gz
jxl
mobi
epub
I’ll add .rtf and .usdz today. I’m also going to move this list into an actual help document somewhere.