Hello,
I struggle with katakana as well, mainly because I rarely come across them.
I added the Wanikani katakana for onyomi script a few weeks ago to try and tackle the issue.
It replaces the hiragana with katakana when you type during kanji reviews (when Wanikani expects the onyomi reading, which is not always the case).
It’s too early to tell if it’s working, but at least I’m exposed to katakana on a daily basis now