I’d like to do my own studying using the WaniKani sentences. Is there some way to get either a) the list of all the WaniKani sentences, or b) a list of the WaniKani sentences associated with the Kanji that I’ve already learned?
Yes, as @jneapan suggests, you can use the API. If you have the Wanikani Open Framework installed to do the heavy lifting, you can put something like this in the console on your browser (adapted from some code to generate cloze deletion versions of the sentences):