There is numerous bits out there good and bad. If you are worried about injuring your horse you usually want to stick with thicker french link D ring snaffles. They reduce the risks of bar pain, top of roof soreness and pinching unlike loose ring single jointed snaffles
There are also numerous straight bars made of various materials (rubber/plastic) that would not cause any harm to your horse as long as used in the right hands. Make sure these materials are in new condition as they often wear away leaving rough areas and can cause soreness
The majority of bits are necessarily fine.
For example, snaffles don’t really do harm unless someone is pulling like mad.
Even some of the leverage bits are alright if the horse and rider are at a point where they can maintain a correct steady contact.
There is not really a magic bit or bridle. Even bitless bridles have their drawbacks.