I've checked some popular crypto sportsbook such as Fortunejack, Betcoin, Roobet, Gamdom, Coinroyale, etc but I cant find the market for the next pope.
However I found 2 sportsbooks that also provide the market for who will be the next pope as you guys can check below:
Shuffle: https://shuffle.com/sports/novelties/custom/religion/pope
Bitsler: https://www.bitsler.com/en/sports/specials/religion/next-pope/simple-168233-next-pope