Send an email to your current health insurance provider and ask them to please reply back explicitly stating if covid expenses are covered. Similarly if you hold an amex platinum etc, email their emergency medical/travel insurance provider for the same. I was able to use this way to basically get a letter stating that yes covid expenses are covered.

But if any of that doesn't work, SafetyWing is a popular one (not sure if cheapest). Covid insurance is a very common thing now so lots of (junk?) insurances exist now which will give you proof (enough for travel) for $20 or so.