These are some Heart Pirate/ Trafalgar Law hospital/clinic/backyard-backstreet clinics AUs that I enjoy out there. They're not necessarily based on the U.S. system (I have one in there, and I'm not American, so mine isn't)—much of the world doesn't have the same kind of system—and they might not be street enough for some, but I feel that there is good writing out there, expressing Law's trauma at being turned away from care, within and outside of systems. I absolutely recommend the first one (I recommend them all, but the first is truly masterful).
I’ve read good hospital AUs, good clinic AUs, and good underground clinic (and alternative) AUs. I agree that he’d help out. I’ve written him both in a (non-American) hospital setting, and in-verse running his own clinic to help the down and out. The hospital was one set up by Whitebeard, etc.
Anyway, my fave hospital AUs that I can recall now:
This one by FS archive is amazing. Outlining the Hearts helping out and working right up to the financial and emotional wire. Independent clinic:
excision (you need to be signed in). Set in Dressrosa, but I’d call it an AU
something’s always going on with pathology: locked fic, hilarious, based on Scrubs, but don’t need to have watched it. Set in a hospital. @thegrimshapeofyoursmile
This one’s ongoing, but the Hearts set up clinics as they go along, and have currently done so between Zou and Wano. Independent players. When the levee breaks.
This is my own one shot, based on a Japanese piece of art, and there is a painting that also features in the fic that is based on a Japanese tradition, so, vaguely set in a Japanese hospital. It’s more an exploration of the characters. screen / shiki-e
Underground clinic care (set in Dressrosa). Features Law, Kid and Luffy Among our Enemies by @purplehairedwonder Art by @generaldevi
Canon-adjacent. Law works hard to get qualifications and his papers published (as an outlaw), and then presents on his work (as an outlaw). Funny one shots, but also touching. Peer Review and Scientific Convention by @nehswritesstuffs Both fics are locked.
Anyway, I think there are a lot of good medical Law (and Heart Pirate) AUs out there (and probably some that are not so good). I know I've missed a ton. The fandom's been around for a while. Looking forward to the stories/AUs expanding in all directions though. I think it's important to keep in mind, though, that not all writers/artists are within the U.S. , so characters, etc. might not face the particular obstacles that those that live in the U.S. seem to. Health care can be restrictive worldwide, though. True.