Well, that wasn’t much of a help for you! In this case, a pharmacist will be the best person to contact.
Have a list of your husband’s meds and his conditions handy, and then at an off-peek time during the day, give a call to the pharmacy where he is a routine customer. You can also ask for a consultation time too! We’ve done that. The pharmacist returned our call after reviewing info we sent.
That way you’ll have more of an idea of what meds might be available should your husband (or you) contract Covid.

There are treatments for immunocompromised people with Covid other than Paxlovid, which is an antiviral.
There are mono-clonal antibody treatments which are quite effective. But I agree with you about wanting to be prepared and in this case, since you aren’t getting answers from all those other sources, a Doctor of Pharmacology will be able to help point you in the right direction. ☺️