It's already in, the problem is that the MoE Hokkien dictionaries are distributed under non-commercial licenses so we can't offer Hokkien support as an easy-to-download add-on but have to package it up with instructions for how to turn it into a user dictionary in Pleco, which we haven't done yet.
But the quick version is that you can add a Hokkien field to flashcards in Settings / Flashcards / Fields and once you do, you'll see a bunch of other Hokkien-related options open up, and you can import a Hokkien database into flashcards.