It’s kind of impossible to read any Japanese text that’s not out of a textbook without progressing to an intermediate level in your grammar studies. Well, not really impossible, but it’d be pretty hard. You can pretty easily look up unknown words in an online dictionary (I started with jisho.org for example), but it’s significantly harder to look up unknown grammar. That’s why I think WaniKani level isn’t the biggest obstacle when it comes to reading, but rather, your grammar level is.
Even manga for children isn’t as easy as you’d think. Sure, the words might be easy, there might be fewer kanji used, but the grammar used is often pretty advanced to a learner (think about it, Japanese kids have a lot more years of Japanese learning under their belt than a beginner Japanese learner, so it’s natural).
I guess something like a so called “graded readers” would be a good approach, or study material for the JLPT exams. I for one did it the hard way, and would often spend hours just trying to read 1-2 pages of manga, getting hung up on unknown grammar, or slang, and having to either Google it, or ask about it on a forum. The further I progressed with my grammar studies, the easier reading got, even while not progressing with kanji that much (I took a 2 year break from WaniKani at one point so I wasn’t even actively learning kanji, but reading got easier the more grammar I learned.)