I actually did some testing of spritesheeting with Nano Banana Pro a while back:
https://mordenstar.com/other/nb-sprites
If you use the editing capabilities and send in a grid of 32×32 cells on a 1024×1024 image, you can get it to flood-fill in each square, so you end up with properly aligned 32×32 tiles. Then you can squash it via nearest neighbor to pull the lines back out, and reduce the palette using something like unfake.js:
But even still it has issues sometimes.
The intersection of people interested in Aseprite and people wanting to just spawn this stuff out of thin air is fairly low!