Possibly I‘m not smart enough to understand, but from what I see is that the implementers intend to leverage existing security architecture of Android/Google and iOS/Apple, respectively- arguably to drive adoption. The document doesn’t state anywhere that Apple / Google account is a requirement to use German eIDAS. From what I can tell, one may (continue to) use its government issued ID card with electronic signature for authentication.

Please prove me wrong, I genuinely want to understand the implication of the linked document.