Frankly, it sounds like you're doing everything you can, and that's a fair bit.
I strongly suspect that the best home you'll be able to find, (best case scenario) is with an ethical, responsible keeper with no more resources at his/her disposal than you have right now. Even if you include all your supplies and they chip in with their available resources, your burm will probably be no more comfortable than he is now with you. The chance of getting him adopted by a super-vet/genius/rich-person/saint is virtually nil.
You are more than welcome to cuss me out over this. But if you're already offering optimal conditions, if there's no procedure available or even theorhetically possible to widen his breathing passages, and if he already feels stressed with a condition that will take his quality of life downhill as he grows, then euthanasia may actually be an unfortunately fair option.
F*** but I hate breeders who breed the brains out of dogs, soundness out of horses and the heads off of burms. Whatever happens, I wish you well.
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0.2 chickens (Falcon & Condor)
0.2 dog mutts (half ownership, only mine when they misbehave, Lucy & Amy)
0.1 Halflinger horse (Crissy)
0.0 Arizona Mountain Kingsnake (coming soon)
1.1 parents
Still searching for 1.0 WC human