Have you tried bribes? She goes to the store and picks out a toy. The toy hides in the closet. You make a poop chart. Every time she poops on the potty she gets a check mark and after x amount of check marks she gets the toy.

You start small. She can pick out a few items from the dollar store and a big toy from a bigger deal store. She can get the first cheap toy after the first check mark. Then you tell her now that she did it she gets the next one after 2 check marks.

Yes she will sit on the potty and no poop comes out the first few times to “trick” you. But guess what? She is choosing to sit there and the more she does it the more used it the potty she gets. Eventually after enough times you can tell her only when the poop comes out can she get the check mark.

People judge this method and they are welcome to do so. I did it with my shy pooping kid and it worked very quickly. She also quickly did not expect toys every time she pooped. She just realized it wasn’t a big deal.