Just the files, links, and non-Creative Cloud fonts.
The process cannot be decerned but may be deduced by studying the file. However, if you used a specialized plugin or script, it would not be obvious. I had a similar situation where I had to send the ID files to a client and I wrote a fairly complicated script (for me, anyway) to work with a database plugin. The code was stored on the pasteboard so I simply did a save-as, deleted the code, packages the file, and sent the file to the client.
David Creamer Adobe Certified Instructor, Adobe Certified Professional, and Adobe Certified Expert (since 1995)