Loading externally packaged levels/assets for mobile

I have seen several discussions on this topic but I wanted to ask based on my specific situation so as someone may point me in the proper direction as there may be several methods to get to this same result.

I am in the initial planning phase of developing a iOS/Android App that would have Unreal embedded. I need the UE4 build/player within the app to be packaged lightly for mobile purposes but have the ability to source in images or assets from a database (terrain, meshes, textures/materials, navigation associated with such) so that thousands individual levels could be loaded/unloaded individually and separately (the user would have access to only one level at a time but our database would hold thousands of specific levels). Essentially, through the app the user would choose the level (generally a 5-10 square km area) the associated data for that level would be loaded from our server/database to the mobile device and then brought into Unreal fragment to play.

I apologize that this has been asked 50 different ways before, I am currently looking into chunking/packaging and async loading as that seems to be the path I should take. My current knowledge base leans more towards blueprint at the moment as I haven’t been able to assign someone more adept with c++ to explore this yet.

I would be grateful of any advice as to which direction to go or areas to research based on all of your knowledge/experiences.

Thank you for your time,
Jared