This is about government-issued credentials. When you provide a digital service in the EU where that service is required to determine the age of a user then the EU wallet is able to prove that the user is above a certain age. Or if you actually need to verify the legal identity of a user, then the EU wallet will be able to provide that identity to you. It is as official as it can get.

If you want to use your own age-verification or id-verification, then you need to rely on face scanning and other creepy stuff. The EU wallet is better in that regard, but it's existence will also mean that the EU and national governments will push harder for people to be identified online and offline. Using the internet anonymously will get a lot harder.