If you really felt compelled to volunteer I heard of people obtaining sponsorship through their community back home. In my hometown I know a couple of doctor offices & small business owners who would love to associate their businesses with a person who volunteers to save lives. Might even get mentioned on the local news?
My wife & I talked about volunteering with Mercy Ship or SmileTrain in early retirement. But I wouldn’t want to be CE with Mercy. I have a coworker who volunteers with Doctors Without Borders & he told me once he was responsible for fixing a portable generator that went down. He said he was scratching his head trying to find the problem & a doc casually stuck his head in the room & told him that 2 people were going to die if the gen wasn’t running before their backup batteries went out. I’ve been pretty good at keeping the lights on over the years but I wouldn’t want the stress of knowing somewhere on board someone is performing surgery