According to KTEL Fokidas site: https://www.ktel-fokidas.gr/gr/nea/item/154-dromologia-poy-tha-isxyoun-apo-14-septemper (sorry, no English version of the article) which mentions the bus routes from September 2020, there's no Nafpaktos-Delfi direct route, but those two hours you mentioned exist for the Nafpaktos-Amfissa route, almost everyday.