I was evaluated by two US transplant centers that function under a government-regulated evaluation regimen, and spent more than a year researching the process.
Neither would proceed with any paperwork or testing without proof of insurance coverage specifically for transplant.
Honestly, I'm not especially concerned with edge cases like "is it possible to get a transplant without insurance if I offer to pay cash?" or questions about what a transplant really costs.
Those are irrelevant academic questions for the vast majority of transplant patients.
A simple "no" would have sufficed.
That 1M "cost" you mentioned isn't actually the cost is it? It's the amount the hospital wants to recover from an insurer. The true dollar cost is much lower.
I'm not saying it's easy to get an organ transplant without insurance, but to say it's impossible without anything but speculation isn't very useful.