I’m not sure what you mean by a modern innovation. What you call chareidism is just strict adherence to halacha and putting limud hatorah as top priority and a chashivus for daas torah. As far as I’m aware, that’s what they’ve been doing since matan torah. The Gra spent 22 hours a day learning, sleeping in half hour shifts over the course of the day. Who is that more consistent with, the thousands of bnei torah learning in kollel and yeshiva, or a guy isn’t so zahir in halacha, watches movies, wife doesn’t cover her hair, etc. (I’m NOT saying all MO do all of those things, but those are all things that aren’t accepted in chareidi circles, and are done by people in MO circles.)
Also, there are things we can point to as changes from the way it was done before when it comes to modern orthodoxy, but you won’t find any new hashkafos introduced over the course of chaareidi history.