hello,
i reviewed your videos, i think that it is appears as if the wheezing is in the oropharynx area. It also appears to be primarily it the inspiratory phase of the purring/breathing.
There are internal medicine specialists who focus on this kind of clinical sign. I am not sure if there are any in your area though? I think the best place to start is at a feline specialists office. They tend to be more affordable and accessible. See if they can help start to rule out things before you jump into a scope.
In my practice for cases like these a typical work up looks like this;
1. exam,,, use your brain,, its your best diagnostic tool.
2. radigraphs,, to look at the lungs.. lots of older cats have chronic lower resp disease,,, and unfortunately, we are also looking for signs of cancer.
3. blood work,, a full cbc, chem, urine and t4.
4. oral exam under anesthesia,, i look at the whole oral cavity, remove a polyp if i find one, flush the nares if the patient has had chronic nasal discharge, and then I also take skull rads, esp of the nose/nasal passages.
if all of this fails to produce any helpful info endoscopy is the next step.. or CT, but endoscopy allows helpful info and you can do something (biopsy, etc) if you find something.
I hope this helps..
PS i agree about your theory and feelings about the corp practices..
good luck,
please keep me posted,, i would love to hear about how things turn out.
PSS i do think that your kitty is a little old for a polyp.
I cured a large hematoma on my cats ear with the homeopathic remedy Arnica mont 30. I believe I just gave it once a day, maybe twice. It took about a week to ten days to completely resolved but there was improvement right away which was steady until it resolved. The ear flap returned to normal. In this podcast homeopath Joette Calabrese mentions that in classical homeopathy, Arnica Montana is always used for hematomas. Cost $8.00.
https://joettecalabrese.com/podcast1/podcast-73-my-time-with-the-banerjis/