What is incumbent upon a husband who broke his fast in Ramadan due to a kidney illness, then in another Ramadan due to the coronavirus, and did not make up the days he missed in either Ramadan?

Allah Almighty has permitted the sick to break their fast, with the obligation to make up the missed days. If the illness is chronic and incurable, then the person is not required to fast but must pay an expiation (fidyah (definition)) by feeding one poor person for each day. If your husband recovers and is able to fast, he must make up the missed days. Delaying the make-up fast until the next Ramadan (definition) with a valid excuse is permissible. However, without a valid excuse, it necessitates feeding one poor person for each day of delay. It is recommended to consult doctors to ensure his ability to fast without harm.