Why does this picture of Ross look like some weird Mandela Catalogue pic…

As mentioned Aseprite has a linux build.

Pixelorama is very similar to Aseprite, but has free builds. Is built with Godot and is open source.

It looks like Aseprite can export a texture atlas, but I haven’t seen the ability to do so in Pixelorama.

For lighting effects there’s an application called Sprite Lamp (also has a linux build) that’s been around for a long time. I haven’t used this one though.

I haven’t done any of these workflows in awhile but I hope that this helps.