contacting medicare for pre-authorization ?

No. All along, we’ve been saying not all procedures and not the patient. Most times, the doc office goes for the auth. If approved, then your billing depends on your specific policy.

You can’t even appropriately describe what the procedure is, in the lingo, nor do you know the exact codes.

Generally, even the billing dept doesn’t know what codes until the doc sends those over.

Imo, this is much simpler than you’re making some of it.
Read what your Plan G covers and expects. In some cases, it supercedes Medicare. In others, it goes by their standards.