Unpack a Unity package
Open a .unitypackage and download the assets inside as a zip, using the paths stored in the package.

Details
A Unity package is an archive with path names inside it. This page pulls out the files that have both a path and an asset, then downloads them as a zip. A Unity project folder, a scene, or a prefab by itself is not a package. It cannot turn those into FBX.

Category: File conversion
Page: /tools/unpack-unitypackage
Text: /tools/unpack-unitypackage.txt

Limits
A .unity scene, prefab, or project folder is not a package and cannot be turned into FBX. Only files that have both a pathname and an asset are included.

Steps
1. Drop a .unitypackage file.
2. Download the zip of assets.

Questions
Can a Unity scene become FBX?
No. A scene is Unity data, not a model.

What is inside the zip?
The asset bytes, named with the path Unity stored.

Nothing is uploaded. Closing the tab drops the file.
The package is unpacked in the tab.