Well I'm looking for the same thing, for a lightweight 2D game engine supporting decades old hardware (the game player is 2MB zipped, 1MB for a minimised build). Animations are likely to be low resolution and seconds long, so a huge decoding library would be pointless. Sure, most users don't care about file sizes, but some (including me) still do. Especially for the wasm and Win95 ports.
I considered libtheora, the library size is good but the compression/visual quality is awful compared to the alternatives.