hi initramfs, i responded to robottoaster who referenced patent encumbered mp4, as alternatives there are vp9 and av1.
image formats are more backward compatible, but at some point one has to ask, how low do you want to go? vp9 plays on iphones from 2020 and android phones from 2010. I think animated avif files are basically av1 video files, like animated webp is vp8/9 video.
Animated gif is playable anywhere, but 10x bigger. For a wiggle blog or website I'd provide animated png alongside anaglyph, or anaglyph only.
There is also animated Jpeg XL *.jxl files for the bleeding edge. It's a pure image format but support is not there yet.
