One more: converting GIF to MP4. A multi MB GIF can be compressed to a few kB of MP4. Most clients play them in the same fashion, so it's an easy win, orders of magnitude less data. Most modern software does this already. If I download a gif posted in Signal it is converted to an MP4.
@β‘ Dee Kay β‘πΈπͺπ¬π§π¨πΏπ§π·π¦πΉ has put in a lot of work on the media code in Amethyst. Aiming your agent at his work there could teach it a lot. He's good to talk with too, he might have some tips.