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?
Negatives help, you can also specify hands be concealed behind objects or whatnot. There really is no reliable method except training larger models, (eg SDXL gets it right a lot more often than standard SD models) or manually editing the image afterwards.