Welcome!
It does of course depend on what your goals for Japanese are, whether you want to be able to speak well (enough), read well, both, etc.
Regardless, basic grammar is necessary for everything (think sentence structure, particles like は, の, に). It’s up to you how late you leave some kind of grammar study, and what resource to use (I used Genki, other people say good things about Minna no Nihongo textbooks as well, some people use online resources like the one Dara linked above, or Cure Dolly youtube videos or Tae Kim’s grammar guide). But personally I think going through at least the very basics early on is good, as it preps you to be able to read or listen later on. If you find a structured course or textbook you like, sticking with it for at least a while is probably the way to go, to get you through the absolute beginner stages.
Whatever your goal is, remember that Kanji is just a small part of Japanese. Wanikani is incredibly useful for it, and just with Wanikani alone you can read so much Japanese on signs etc. in Japan, but you won’t be able to communicate at all. For that, you need some basic grammar study, and listening/speaking practice. Also, there is a lot of basic vocabulary which Wanikani doesn’t provide you with which you will eventually need to know. There are beginner resources for listening, such as Comprehensible Japanese, or Nihongo con Teppei, and some people use services like italki for tutors to practice speaking with. There are language exchange services like HelloTalk (not sure about others but I’m sure they’re out there) which you can use for free instead to practice communication - you can find people to message, talk with, etc.
If you are interested in getting into reading, I see this guide posted a lot for beginner reading advice: Joining the Absolute Beginner Book Club: Preparation and First Reading Experience Expectations - Japanese Language / Book Clubs - WaniKani Community. It’s up to you again as to when you start reading. Satori Reader is another option I see people use, for language-learner aimed post-beginner reading content rather than native material.
Hopefully some of these resources might be helpful. I remember being in your position and not knowing where to start - there’s so much information out there, and so many conflicting opinions. But as long as you get some basic grammar and vocab down, and try out different things, it gets easier to figure out how to move forwards! Try to make sure you know what your goals are so that you can think about how to reach them. Sticking to resources for enough time to get benefit out of them is important, but if something doesn’t work for you, don’t be afraid to change.
Good luck!
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