> Governments are cementing a monopoly they claim to oppose
Duopoly but yea. Because there is no third alternative. Microsoft failed/gave up with Windows Phone. The people trying to fix secure government services can't really tackle that issue, but the systems needs to be built now anyway.
> but the systems needs to be built now anyway.
I question that premise.
They can't tackle issue oft establishing a 3rd popular mobile operating system, true. But they could support Desktop Linux or AOSP.
Windows Phone wouldn't be much help here, still an US company.
There are viable third alternatives which do not require building a full smartphone stack. The national eID in Denmark, MitID, is an app "protected by" Play Integrity, but at least there are two non-smartphone alternatives available in the form of either a TOTP code generator or a FIDO2 chip which you can get for free if you can't or won't buy a smartphone.
Age verification solutions could also be built on dedicated hardware tokens, even though the tokens required to build a ZKP or blind signature based solution may not be available off the shelf right now.