Klipme claims to do this exactly. I've been on the lookout for such tools, to generate reels/vlogs from my huge raw content. Happy to bounce ideas and contributing to build one.
I checked Klipme..it can generate shorts with little bit editing that only we need to do.
I was looking for something where that editing(B-Rolls/transitions/subtiles/BG Sound) also get added by AI .
The company behind it has more robust cloud tools too, meant for film studios. If you're serious about building this, please reach out using the email in my profile.