Initial attempts to search for this were frustrated because my search engine kept trying to find rhymes for "FOSS" or "Open Source"
However, I did find an app with credits that showed what libraries it used.
In particular, this one might be up your alley: Carnegie Mellon pronouncing dictionary. It looks like you'd still have to combine it with an existing dictionary in order to find the rhymes, but at least you can get the pronunciation
The problem with Levenstein distancein in this context is that it does not consider phonetics.
Sometimes differently written words rhyme perfectly and other times identically written words have multiple meanings and distinct pronounciations that do not rhyme.