Animated webp decoding is not widely supported, but we discovered a method this week and I plugged it into my old (slightly janky) native animation viewer. I have made it work just like the for gif and (a)png, where, within hydrus, images and animations will count as different filetypes. On update, all your existing webps will be queued for a rescan. If they are actually animated, they will become 'animated webp' and get num_frames and a duration, and they'll play animated in the media viewer. Let me know if you run into any trouble with it!