This is true and possible. You can push your teeth everyday in the morning and before you go to bed. If you have slight imperfection to your teeth. It will align accordingly. You just need to push/pull it consistently in 1 direction.
Note: Push and pull means no backward and forward motion at a time. To avoid loosen the gum bond.
Imagine that your teeth is literally place in a gum. Any object place in a "gum" or clay, will move when something is pushing or blocking it.
Its the same concept when you eat hard foods, it will make your teeth slightly forward on the upper teeth.
The changes and movement of your teeth will move minimum of 1 millimeter in a month. If your good and understand what you are doing. You can move your teeth up to 3mm in 1 month.
Logic: The frequent you push the better and faster is the result. Pushing must be hard enough that you can feel it is been pushed. But not to the point that it will break or cause pain of your gums. When your gums or teeth feels a bit of pain when you push. That's good, but you need to wait another day when it doesn't hurt that's the time you need to push again. believe me, it will work if your consistent.
Try not to use it when biting use the inner teeth or whichever you want to fixed.
You can use hard object. Just make sure it will not hit your gums (sometimes it will slide straight to your gums). I use wood pushing it with control. But I use my finger sometimes. When you see your teeth is bleeding, then stop. but don't panic. It will heal. Just wait another day and continue when it doesn't hurt anymore.
The first day or first week of pushing must be a hard. ( Because your teeth has been rooted to this gum for a long time). Always bear in mind not to push it in abrupt manner. Gradually push from smooth to harder and stay there in 5-10 seconds. Do it repeatedly within 5-10minutes after you wake up. It means around 10-20 repetition in 5-10minutes in 5-10seconds push/hold. It's recommended to do this facing the mirror so you know which angle direction you should push. You have to be strategic in direction of pushing, so you wont be wasting time.
Good luck! This works for me. Except maybe if you have very sensitive gums. I'm saying that it is possible. But i am not saying it will fit to all. You may customize it accordingly. know your teeth or gums first. This is no difference with braces, except that braces are more consistent. So if your consistent. It will work the same.
If you have braces it will speed up everything.