Now there is that kind of chest expander on the market, which is an unscientific magic way and will cause physical harm.

Your right shoulder is probably dislocated habitually, so you can't practice any more. Stop it.

Hold your right arm above your head for a few minutes every day when you sleep. When you move your right arm, your bones will stop ringing and you can start exercising again.

And don't use arm extension. The simplest and most practical way to practice chest muscles is push-ups.