I can't answer your question, but here is our experience (I'm on Medicare, my wife isn't of that age yet).
We have remotely consulted with a doc in CA for years. He has 3 levels of charges.
1. In office, which he accepts insurance/Medicare.
2. Remote, which is cash pay per consult.
3. Concierge, which is an annual fee.
Around April/May 2020, we had to sign a form saying we understood our remote consults were cash pay.
Not sure whether different care levels are billed through different entities. I'm 98% confident the concierge service is, though I don't use it.
I would presume you'd need to at least pay the non-Medicare part of the charge, or have your supplemental insurance cover it.