Thanks for the shout out @Kumirei 
And ya I wrote this integration last year and posted about it here: Get notifications (emails, text, Twitter, Slack, Discord, etc) whenever you have new reviews, lessons or you level up - #2 by nextlevelbanana - but I think it was “officially” launched recently.
The code for it is here: GitHub - mike-solomon/zapier-platform-app-wanikani: Zapier CLI App for WaniKani - and I’m happy to add any other triggers or actions y’all wish to see ^.^