Is it possible to import Unity .asset files into Blender?

Hello,

Is there a way to turn a unity .asset file into a .fbx or to otherwise allow their import into blender?

You can, Install the FBX Exporter package from the Package ManagerUnity Registry.

Then you should be able to select any object in your scene and export to FBX.

For more complex use cases you may want to use USD file format which both Unity and Blender supports.

https://openusd.org/release/intro.html
https://docs.unity3d.com/Packages/com.unity.formats.usd@2.0/manual/index.html
https://docs.blender.org/manual/en/latest/files/import_export/usd.html