Xu Fu made herself an itabag of Yu and also made a Xu Fu itabag for Yu who thanked her and then made a Yu itabag for Xiang Yu

Iron-Blooded Orphans is a pretty good entry point. Theres no connection at all to older Gundams and its had some of the better characters and story in recent entries

If its gonna somehow look like a cat you can also just go full cat and make it a Maximal. Though I always felt those were more complicated going from robot to animal form