At least far as it comes to privacy Apple and even FB, MS and Google to an extent share the same interests as their users, unlike the EU bureaucrats who just seem to be salty because they are unable to exert control over society and justify their existence (they might pass some decent policies while they are it that's just mostly a coincident..).
If Chat Control goes ahead long-term that will outweigh any benefits DMA might have.
DMA, like any other regulation that preceded it, was severely lobbied down. It happened in spite of EU. There is too great of a democratic consensus for it to be completely ignored. Do not get this wrong.
I wouldn't expect it to any time soon either. They'll likely find a way to maliciously comply.
My bet is that they'll only allow "Trusted Partners" to interact with their network, and you'll need to sign a contract with one of these partners to connect to WhatsApp. This contract will have pretty much the same terms as signing up with Meta directly.
Are you talking about the same EU that just passed the DMA? That must have been some really nasty food poisoning then!