A sprite animation editor with a procedural approach. You can layer different animations on top of each other, as well as multiple sprites(not seen in the examples below.) No GIF export, but if you have the means to make GIFS from image sequences, then you're good(you could theoretically dump the output frames/spritesheet into Bitmapflow and then export that as a GIF.)
A node-based pixel-art software. It's pretty basic on its own, and it's no longer updated by the creator, but there is still a small community forum where users have uploaded their own custom-made nodes.
A smattering of textures I've made using Tilemancer over the years. The Brightness(made by user navot) node makes up 80% of my workflow.Link to Tilemancer's itch.io page
Pixel Composer
Another node-based pixel-art software, not dissimilar to Tilemancer. Unlike Tilemancer, though, Pixel Composer supports animation, and is actively updated. It's got a lot more nodes than even I know what to do with, from 3d transformations to fluid simulation nodes to feedback loop nodes, in fact as of two days before writing this there was a strand/fur simulation node added.
Pixel Composer is so far the only item on this list that isn't free, but for 5 US dollars it's well worth it.