Tbh I'm currently volunteering as a ward assistant in a hospital and even though, yes it often is just pushing the food trolley around, you shouldn't dismiss it because it's great for patient contact and also talking to other health professionals. Imagine being in a hospital environment long-term as opposed to just a couple of days work experience- after settling in, you'd get to see far more of what doctors/nurses do and how a hospital in run than in a couple of days. The staff there also said to me that if I ever have any questions about medicine I can always ask someone, as everyone's very friendly, and that they can also help with getting some shadowing etc. You're actually part of a team rather than just stuck on the side even if you're directly observing, which to me seems a lot better - you can actually get some hands on experience, and you're actually doing good for people.
It's pretty invaluable, and I'm finding it really interesting so far.