my source is that google/alphabet is in the top 5 biggest companies in the world, I consider it quite within the realm of google to decide to solve having open source drivers for some bluetooth crap. regular small guys can reverse engineer more complex stuff in their basement, google can fund that, or do it themselves, or outright buy the bluetooth companies should they want to.

my spidey-sense is telling me that a giant megacompany that dwarfs bluetooth companies could probably manage to solve this, and easily at that

Your spidey-sense is wrong, for the reasons I specified. It is not economical to do this. The effective way to solve open source Bluetooth drivers is with a carrot, not a stick, regardless of how satisfying it would be to try to beat bad companies with it.

I do not believe that it is beyond google to produce bluetooth drivers, or even bluetooth hardware.

It can no doubt solve it cheaper, but it can for sure solve it