German implementer here. We have to use some kind of attestation mechanism per the eIDAS implementing acts. That doesn't work without operating system support. The initial limitation to Google/Android is not great, we know that, and we have support for other OSs on our list (like, e.g., GrapheneOS). It is simply a matter of where we focus our energy at the moment, not that we don't see the issues.
Do you realize where this path is going?
Certain European governments would have greatly benefited from KYC/attestation in the late 1930s had it existed.