Something to keep in mind that maybe experienced PAs could clarify would be how a school with no standardized test requirement would view an applicant with volunteer experience like what you mentioned vs HCE. I would imagine that a program that didnt require the GRE would probably be doing so in order to place more of an emphasis on the merits of a background in a health care setting. A candidate with that has basically been vetted to some degree by their employer and shown to be worthy of being trusted with patients. As a result, they dont have to prove as much. Showing up to read to kids or sit with old folks doesnt require discipline or a lot of structure, and could easily be contrived. I've no reason to say it would be in your case, but just the fact that it wouldnt automatically say anything in particular about you without you filling in the details makes it something I wouldnt rely on.
Medical and dental programs seem to like to see a lot of volunteer work but they dont recruit as much directly from health care (although there are plenty of med students who are impressive exceptions to that). You have to expect that the competition is going to have great grades, scores and HCE that they bring to the table that shows well on paper and in person. To top it off they pulled every string and sprinkled on volunteer work just to put them over the edge. A lot of what Ive heard on here indicates that PA isnt just med school-lite, but a different species. You could look for the exceptions, but when you get into the ring with these folks in this environment, you are up against people that are hungry for it. You want to make yourself appeal to the broadest segment potential evaluators.
I only mention this because Im in the middle of all this as well, and among a lot of folks that fancy themselves to be good PA material. One gal I work with left my dream PA school after one year to be a Med Tech for gosh knows why. I have fine grades, great responsibilites and experience, and people that would go to bat for me. Despite all that, Im still nowhere near counting on getting in (my top choice is ten minutes away from my door, but tends to pick up really bright younger kids with little HCE). Maybe you fit into that category and will do just fine.