“I know shuls.”
Have you seen it? I’ve only heard of it. Even from Chabadskers trying to defend Chabad. But I’ve only seen a mumbled chirping like half-song. Less than Barchu after maaariv in Bobov. I’ve seen pit said privately immediately after shmoneh esrei. Etc. Same goes for na nach. I would not (yet) consider it part of their liturgy. Either way, it does not compare to others that changed the way the lein, chazaras hashatz, and took out and added at will.