With stories you'd probably index the videos, then use kind 1111 comments on each video. You could have collections of stories, maybe pinned to a user homepage. (I don't use Instagram so forgive me if I'm misunderstanding something.)
Yup, no you got that right That's literally my plan! And that's also all I really need. The reply section for the full story (which is bsdically a 🧵 of visual frames, not videos btw) is something that adds more confusion than it'd help with UX. And I also don't have pixel space for it neither. So still definitely using 30040 for it, just without those general replies.