maybe I did misread you. You lamented the "hand over" of "the entire German gov mobile communication stack" to Apple. But what you show is BSI audited iOS and verified their own Indigo solution to be compliant with their requirements for handling VS-NfD documents (one solution of a handful of others).

So VS-NfD bits will pass that software stack sure - but as I was sceptic if "the operational part" was handled by Apple, I don't see this supported. An MDM will set endpoints for email/carddav/caldav to .de gov servers, I hope :)