From the filing:
The stolen files, NAMED: >DisplayNotes.key — "several hundred pages" on Apple's custom display power development program >Architecture analyses. Fabrication decisions. Testing results >Engineering data for an UNANNOUNCED Apple product: 'touch, display, and power systems" >Final.key + V2.key — compilations of two undisclosed Apple R&D projects >and those are "only four of the dozens of proprietary documents Mr. Liu stole"
Also
>OpenAI "directed a trusted Apple partner [name redacted] to perform [Apple's proprietary metal finishing] process for them, knowing it was proprietary to Apple... because they were involved in this partnership while at Apple."
So apparently yes, OpenAI is very interested in Apple's hardware. I don't see any references to software secrets in the filing, it seems to be entirely about hardware.
I had a quick look at the texts released by OpenAI, and it looked to me like a former Apple employee was sharing info and documents with a current Apple employee in an attempt to help out.
I do not know whether this lines up with the claims of stolen files.
The second part reads to me like they asked some company to perform a special metal finishing, knowing that they perform similar work for Apple.
I am no lawyer and I do not understand what is proprietary to Apple here, it just does not sound that big a deal to me.
Now that is a charitable reading. Maybe OpenAI ruthlessly stole Apple's trade secrets. I do not know.