>>2252411There's a few methods here if you're interested:
https://rentry.org/aiemtee#rendersThe best method in general is using paths in GIMP to outline and mask the subject. It's also somewhat more convenient than magic wands, counterintuitively, because the paths can be modified after creation, unlike a selection.
Here is the .xcf file for this render. Should shed a bit of light on the process, including the 'lazy' way of cleaning up the outline with a stroke along the render path.
https://files.catbox.moe/t0r2vz.xcf 