Many veterinarians are willing to work out some kind of payment plan with people - they want to give the animals the care they need. They will work with people. They’ve worked with my mom and it wasn’t just for trivial problems. They also sometimes don’t charge for everything, or charge cost for some things.
I spoke with my veterinarian friend. He says he is a general practitioner and not able to do this kind of work, nor does he have this kind of equipment. He had already heard of this case and said the dog was at the right kind of specialist, but he thought it probably was cancer. So it really doesn’t sound promising.