There should be a download button on emotes that allows you to choose which file format it's saved as. although AVIF and WEBP save bandwidth while being used in chat, most programs or websites (discord, adobe software) still prioritize GIF support. It would be nice to have a "download-as" button so that you don't have to use an online converter to get an emote as a gif.
I understand that some people may not want to have their emotes be easily used off-platform, so maybe allow users to toggle the download button on emotes that they upload.

advice (mostly for AfterEffects users): If your program doesn't support export to webm, webp (i.e. nothing related to vp8), you might be able to export to mov (quicktime) which supports lossless+alpha (QT-RLE, argb pixel format). Thus you don't touch gif at all. At least AfterEffects supports this format. The file might get big since it's uncompressed though.