A lot of didactics is quite mathematical, but a lot is also far from it.
Stuff like different ways of understanding division or Janvier-table of transformations between different representations of functions would, to me, feel at home, while something like TPACK-model of teacher knowledge or gender differences in mathematics classrooms feel less so.
I would be positive to the didactical stuff that actually has mathematical content in it.
I am skeptical towards the more sociological or pedagogical content, which might be about mathematics, but not really mathematical.