Also, I think saying that class + model + voice = companion. I think a ton more goes into it than that. The need to design quests around said character, give them purpose in the story, have every companion be able to interact/banter with them, give them a purpose in camp, potentially write a romance for them, consider potential branching paths that they open up, etc.
Halsin has most of that already: He has a quest (shadow curse) and was investigating the tadpoles, is already in camp, and possibly has a romance (based on a tweet his voice actor made and then deleted). That would leave only banter, barks, and other interactions from your list.
