For the record there’s chabad non-Lubavitch that you can get into, eg the mesorah of the Rogatchover , ”
For the record the Ragatchover had the same mesorah as all Chabad had only he chose a diff rebbe. He did go to the Tzemach Tzedek and then to the Kapuster.
Asides that, Rav Chaim of Brisk was very close with the Rashab as well. So was a Rav Itzele of Volozhin with the Tzemach..