welcome. you may want to look over at this other thread about uploading videos. there’s some discussion over there about other file formats that could replace animated GIF, such as APNG.
my sense is that video in any form (including animated photos) is just not a high priority, and i think i’m beginning to understand why it’s not a high priority. lately, i’ve been uploading short videos to YouTube and linking those videos to some of my observations (ex. https://www.inaturalist.org/observations/66154560). as far as i can tell based on YouTube analytics, even though almost all of these observations have been identified and so have had at least one other person (besides me) look at them, no one has bothered to look at the videos from iNaturalist. so i think the reality is that videos might be nice for yourself, but the average observation probably gets very few views and even fewer views by folks who would be interested in viewing a video, even if it is provided as an option. so if still photos will do, video is probably just not worth the extra effort and infrastructure, if the actual viewership is so low.