This is just straight logic. I'm viewing it as if I was Apple. Just as I would view it if I was Google, or if I was Micro$oft. If you are running a company. You have to run your company. Not someone else's. It wouldn't make any sense to depend upon another company for your companies success. You should depend upon yourself as much as possible.
For a long time Microsoft just made the OS. Google was primarily a search engine. Apple always made the OS and the computer. They all branched out into the tech landscape with new products and software offerings. And when it made sense to offer something any one of them made. To work with any other of their competitors. They did. And if it didn't make sense (cents or dollars). They don't.
None of us are able to determine what that challenge would be to Apple to support third party makers in this space. And since every expense has to be valued against a return on investment. You nor I nor the EU can say "just do it because you can". And this would have to be continuous support. Not just a one off. Not only because it would be advertised as such on the box. But, because people like Linus would immediately go from "Thanks Apple", to "C'mon Apple, this is BS! Fix my old AirPods on this latest version of Android and Samsung S33ue.2 Ultra Galaxy already!! It's been seconds since it's been out!!". It's just a VendorID flip!!!! Meanwhile the whole way Bluetooth works on Android changes or breaks something basic that used to work just fine on older models. Or the OS on Samsungs phones breaks compatibility in a way not expected. And on and on. Just buy a pair of Beats.
Our freedoms as a consumer is in being able to purchase what is available as it is. You're not owed anything beyond what was promised by the vendor/company that sold you a product. Expecting it to just work as they advertised it to work on something they made. To something they did not, is not a reasonable expectation. It maybe something you and others want. But, it isn't something that should be expected. They didn't sell it to you with that ability. If you want to hack it to work, go for it. But that's an on the consumer thing. Not a "I spend $250 on these pods and it should work on things other than what was listed on the manual!" thing.
Which is why Apple likes to be vertically integrated. When something changes. They can fix it across the lineup. We would expect there to not be a break but, when it happens due to changes. They can address it faster than anyone else.