We have two top dogs who can do almost anything and are "open source",
i.e. everyone can even take part: "GIMP" + "Krita". These are very complex,
with layers, layer groups, and a lot of filters, plugins, scripting, etc. GIMP
focuses on "raster image editing" - similar to Photoshop, but more
professional (can also use the HEIF format). KRITA has focused on the drawing
itself.
If these are too complex for you, you can go to the much simpler programs
"chasys draw IES" or "L-view" or "Pixopedia".
