Could it be made possible to get the readings in katakana when learning kanji and vocabulary?

I don’t think there is a way to do this natively, but there is a script that switches all on’yomi related readings to katakana automatically:

It works really well. And maybe there is another script that will switch all possible usage to Katakana if you look hard enough, but I wouldn’t do that as it might get a little confusing especially for words in Wanikani that use Katakana already.