Question Regarding Publishing

Hello, I have a question about transferring assets from the Unity Asset Store to Fab.

I currently have around 25 large asset packs made for the Unity Engine, and they are also available on Fab, buut only in FBX and Unity Engine pack. Some of these packs contain several thousand models and fully prepared maps.

If I want to release my asset packs on Fab in a version for Unreal Engine as well, do I need to recreate the full maps the same way they exist in the Unity version? Or is it acceptable to simply include the models, set up the materials in Unreal, and publish the pack without a ready-made level (even though the Unity version includes a full map)?

Also, is there any simpler workflow for this than manually recreating everything, which could take several weeks of work?