I feel there’s some kind of miscommunication going on here.
Probably I’m not understanding what you are putting forward, but to be clear: They are not doing this because they want to. They are doing it because they are forced to do it by the DMA.
It’s true that allegedly they were working on some kind of interoperability layer already. For years now. But no evidence of it being more than lip service to avoid being regulated has ever surfaced - as far as I know.
Which would have been in line with your “Do Nothing”.