voluntary
What does that even mean? I don't think anyone is proposing mandatory, internet-wide age verification. It's 'content based'. Some content is hidden behind age checks. It doesn't make sense to prove you're NOT 18. Either you prove you're 18/16/21 and get access of you don't prove it and you don't get access. At the same time requiring every website to provide 'non-adult' version also doesn't make sense (like pornhub would have to offer child safe version?). Same with social media bans - everyone below 16 is banned. What would "voluntary" check look like here?
equivalent alternatives for citizens who do not use a digital wallet
So it comes down to some alternative implementation of https://ageverification.dev/? It's an open standard. Doesn't it allow for implementations not based on digital wallets? I think that if that's the demand then it would be better to specify it clearly instead of mixing it with demands that the current legislation and implementation already provide.