Right to repair. Hasn't happened because it's not a right yet.
Alternatively maybe anti trust, since using your monopoly on hardware to get a monopoly on software which is the essence of anti trust anyways. Hasn't happened because anti trust enforcement is really weak. Probably also doesn't force documentation.
Alternatively copyright and patent misuse, which is using your government granted monopoly on creating the exact hardware (copyright), or some of the features in the hardware (patents) to get a monopoly in an adjacent area (running software on that hardware) voiding the copyrights and patents. Hasn't happened because while the law exists (in common law) the courts apply it very conservatively. Also probably doesn't get documentation, just the right to run things on it.
Alternatively an interpretation of the quid quo pro of intellectual property (i.e. you disclose something in exchange for a temporary monopoly) being interpreted more strongly, such that you have to disclose the details of the internals to get intellectual property rights. Hasn't happened yet because today the quid quo pro isn't interpreted that strongly.