It’s not for everybody but I think a little Cure Dolly on the side complements early WaniKani fairly well. It’s extremely light on vocab so you can really focus on understanding the grammar.
I remember trying Genki I and Tae Kim very early on and my inability to understand the vocabulary made it more painful than necessary.
By the time you get to around level 16 you’ll have a very decent kanji base that should make dealing with that stuff much easier. Why 16 precisely? Because that’s where you learn the ever useful 書!
Last year I made this post showing the kanji used in Tae Kim’s grammar book and when they’re taught on Wanikani:
It’s a bit outdated however because some kanji have been reordered on WaniKani and are now at more “reasonable” positions (彼, 俺 and 誰 were all way too high previously).