You can get Supplemental Plan F through many insurance companies. Ours is through Mutual Of Omaha. Used to be AFLAC (until they stopped this service in TN). We almost chose State Farm, but objected when they changed white Jake to black Jake. When we were researching, the different plans were very close in price to each other.
...actually Plan F is closed except to grandfathered oldsters just coming into Medicare. Since the pool is closed you want to be in Plan G anyway since that is where all the youngest MC beneficiaries who want full coverage go. There is also a cheaper Plan G High Deductible for healthier folks that done expect surgeries/hospitization at 65-70...
The extra add-ons of Vision, Dental and Hearing are available only with the private Advantage plans. Been a Broker since my disabled late wife was put on MC for her cancer battle. 10 years later happy to give you my opinion on plans if anyone is about to sign up.... ymmv