The app is a bit dated but it’s functional. One thing I would recommend if you do use it is to skip the Kanji decks entirely and start with the beginner deck.
I’m enjoying an app called Bunpo (not Bunpro) for grammar. It’s free and uses the SRS system. I usually do it on my tablet in 5-10 minute blocks while watching TV. It has some flaws but it’s good, especially in tandem with a textbook like Sou Matome or as a review. It doesn’t re-teach any kanji. There are also furigana that you can turn on or off.
Thanks for the replies everyone and the suggestions. It does seem like there aren’t many things out things out the for grammar as nice as wanikani is for vocal. But I’ll keep doing my best!
I used Satori Reader and I think it was a fantastic resource to bridge my way from basic textbook info to reading real visual novels and books. That said, while their scattered grammar explanations are good, and they’ll split apart every character of a sentence for you, if you haven’t really learned the basic grammar yet, it’s probably going to be a little too much to learn all at once unless you have a pretty high tolerance.
Bunpro I haven’t used, but it’s good if you want an SRS for grammar, though common opinion seems to be that it’s not great to learn from as a first source. Generally people seem to use it to review things they’ve learned elsewhere, or look up its topics in more detail elsewhere.
If you’re looking to learn early grammar for the first time, you might want to look at Human Japanese (same creators as Satori Reader, and going from it into that is designed to be a pretty smooth path I think). It’s not without its caveats, but my impression is that it fits what you’re looking for.