I do not think thumb or finger sucking mis-shapes teeth. I sucked my thumb and needed major orthodontic treatment. My son didnt - and still needed just as much OD treatment. As I understand it the reason we had buck teeth was because our jaws were small, we both had very high palates and as a result our teeth were overcrowded. In both cases OD treatment started with two teeth being extracted, one each side at the top, and then everything was pulled back. We both had to have all our wisdom teeth out for the same reason.
My daughter put her middle fingers in her mouth, hand palm side up with the two middle fingers hooked behind the front teeth and her first and last fingers braced the other side, if anything should have distorted her teeth that should, yet her teeth are perfect and she has had no problem with her wisdom teeth.
No experience of dummies as neither my mother, myself or DL used them