I saw comments elsewhere saying Kentucky only disallowed governor appointments within 90 days of an election. So, if he dies today, the governor, a Democrat, can appoint a replacement who will hold the office till whoever wins the November election replaces them beginning of next year. If he dies in 3 weeks, that's disallowed and a (special?) election will decide his successor. Bear in mind that my "source" on this is: Some other people on the Fediverse said so.