Japanese from zero uses a “progressive” approach, meaning it teaches kana in each chapter and fills in words with the kana you just learned. In this way, it is able to teach grammar right away alongside kana.
i.e. if you learn い then they write “dog” as “いnu” until you learn ぬ as well.
I went through all four books and since I started from literally zero, they helped me a lot. But people who already learned hiragana and katakana may find the approach a little distracting.
However, the grammar is roughly the same as any beginner grammar you’ll find in genki, taekim, etc.
JFZ 1 teaches hiragana + grammar
JFZ 2 teaches katakana + grammar
JFZ 3 and 4 teach kanji + grammar
For “beginner grammar” JFZ 1-4, Genki 1-2, and most of tae kim are roughly equivalent I would say.
“Intermediate grammar” would be things like Tobira, An Integrated Approach to Intermediate Japanese, and the shinkanzen master N3 and up.