Could rapping or beatboxing help relieve Parkinson's symptoms?

Parkinson's. To my knowledge there has not been any definitive research on this. Some researcher think that continued use of memorization and repetitive movements may help the slow the progression of the disease. If you like singing, go for it!
Fall precautions. Most pd patients would have a hard time trying any if these. Try and see how it goes - as long as you take fall precautions.