What counts as clinical hours?

I know the basic things like hospital volunteering, nursing homes, cna, emt. But what about more unconventional medical related places such as physical therapy, slp therapy, and other medical related places to volunteer?

Also, what separates shadowing from actual clinical hours? It's kind of hard to do any work that requires emt cna or ma certifications in the state I'm in as you need to be 18.