No financial advice, especially as I'm in Canada. FWIW, I will say my very low-income parents never saw a bill. Yes, we pay for health care by our taxes, but for our family we were very glad for our health care system and still are.
I just wanted to respond as an adult burn survivor. I had 60% of my lower body 3rd degree thermal burns, plus 3rd and 2nd degree on my chest and left hand. I'm 42 years old now and though there were many grafts, compression stockings, etc. growing up, I'm completely fine (though scarred physically) now. I actually could have had more cosmetic/reconstructive surgery done, but I feel completely comfortable in my skin! I wear my burn scars proudly. It was WAY harder on my mom and her fear after the accident was much harder for me in every way than the actual accident and surgeries.
FWIW, I hear you say you do natural therapies. Now is the time for that! I had to see a burn specialist when I became pregnant with dd, because there was concern my skin wouldn't stretch across the tight band of scarring on my belly. Well, it did. The doctor said I'd probably have lots more stretch marks than average. Well, guess what? I didn't have a single one!! I credit my sister, who was a naturopath, with literally saving my skin. I am badly scarred, but my skin is supple and, I think, beautiful! Oh, and I don't blame anyone for the accident, though my mom blames herself. I made it just fine and so will your son. Much love to you.