While this might not be exactly what you’re looking for, someone has made a userscript in which one of the features is audio for the sentences.
[Userscript] Advanced Context Sentence 2 - WaniKani / API And Third-Party Apps - WaniKani Community
Depending on your browser, there are a number of voices available, which is one of the reasons I’ve moved over to Edge primarily for when I’m doing WK reviews, since newer versions of Edge have the “natural” voices available (if it says “[online]”, that’s the natural voice I’m talking about).
This also has coloring for the words you’ve learned.