one of the tricks I was particularly happy with for my website (took a bunch of research to find out how to do it:
<picture>
<source media="(prefers-reduced-motion: reduce)" srcset="https://media.lune.gay/site/banners/e.png">
<img loading="lazy" src="https://media.lune.gay/site/banners/e.gif">
</picture>
can also be wrapped in a link for a clickable animated button.
I'm working on a new one (potentially), so it's fresh on my mind. I try to post about tech stuff a lot here so people can maybe get ideas for their own sites; especially want to do that this last month.
sorry to expose to my cognitohazard-level pile of jinja macros, but if you want to see how I generate the full set on my site:

by