@d_Wooluf has it correct. It you don’t publish a standard it isn’t a standard. Nothing about it will be secret. Instead, all will be trying to tweak their chip to have added features to try to get a bit of a premium for their product.
Apple bought a chip company years ago that did such tweaking. MFi operated on top of the BT4 standard in such a fashion. It served the full BT4 spec and above and that help Apple capitalize on having not only MFi but a feature rich and reliable capability with BT4 enhancements.
All the standard does is specify the minimum requirements that hardware and software types can rely on being available.
At every level, there will be attempts to differentiate their product with outstanding reliability or improved features. Going from BT4 to BT5 just reflects the need and refinement that’s taken place or come into being in the interim.
Apple is proprietary and does what it wants. Google owns Android and will incorporate minimums in future OS. It is the real source for how fast all that happens. They will set an actual minimum standard. They will do this by putting a feature in the standard and not certifying that a product meets that standard.
Understand that MFi is baked into the Apple O/S. It isn’t an App that you or I might write to run on it. To do an App goes through an intermediate level with limit access to the base hardware/OS via the API. While MFi operate using the core system. That is a large difference in speed and priority that users of the API don’t have.