In Midjourney I did try to add things like --no deformed, disfigured, malformed or hands have exactly 5 fingers each in their correct anatomical places to the prompts but with no success.
Do you have any tricks to make those models generate plausible looking hands?
Control Net on Stable Diffusion has a “hand and body” pose. You can individually place fingers if you use some other extensions, or you can find a real-life picture of someone whose hands and body are posed the way you want them and use that as a template. That might be over-kill, though.
At this point though, you might as well skip AI and commission an artist (photographer, painter, fx).