I made a web site for making animated gifs. And you can easily edit the samples I provide.

https://editablegifs.com

I've posted a couple assets from it, here:

https://opengameart.org/content/explosion-gif

https://opengameart.org/content/animated-digits-as-gifs

I attached are some captures from the editing process when you open https://editablegifs.com/gifs/edit/digits-1

When you select an image to change, you can upload your own, or choose from a list.

I'll be adding more as I think of things that can be useful in games.

Taking requests.