Before i started with WK, i discovered “japanese from zero” on youtube. Its a teacher who is working on 5 books for like 25 years now based on students feedback. The best thing is, that he explains everything on his youtube channel in his guide “japanese from zero book 1 - 5”. And i mean litterally everything. The books are mainly for practice. So you get everything for free until you really want to work with the books too. Currently im at the end of book 2. It helps alot to get into the basics and its also well explained. Well there are many ways to learn out there. Just give it a try and see if you like it.
Basic grammar is super important for WK too because its convenient to know how verbs are formed, how you recognise a noun or diffrent kind of adjectives. Also the example sentences will make a lot more sense to you^^
I would also recomment the blog “Tofugu” made by the creators of WK.
And you should definitely check out the ultimate Wanikani Guide from “jprspereira”.
Have fun 