We shouldn't need Age Verification checks for adults in the first place.
Create a better, standardized, open-source parental control tool that is installed by default on all types of device that can connect to the web.
The internet aspect of the parental control should be a "Per Whitelist" system rather than Blacklisting. The parents should be the ones to decide which domains are Whitelisted for their kids, and government bodies could contribute with curated lists to help establish a base.
Yes, there would be some gray area sites like search engine image search, or social media sites like Twitter that can allow you to stumble into pornography, and that is why these devices that have the software turned ON, should send a token through the browser saying "Parental Control". It would be easier for websites to implement a blanket block of certain aspects of their site than expect them to implement whole ID checks systems and security to make sure that no leaks occur (look at the TEA app) like the UK is expecting everyone to do.
Also, I'm for teenagers (not little children) having access to pornography. I was once a teenager, every adult was, and we know that it's a natural thing to masturbate which includes the consumption of pornography for most in some way. Repressing their desires, their sexuality, and making this private aspect of their life difficult isn't the way. Yes, yes, there is nuance to it, (very hardcore/addiction/etc) but it should be up to the parents to decide with given tools if they trust their kid to consume such a thing.
As for the tool itself. Of course we have parental tools, but they can be pretty garbage, their all different, they're out of the way, and I understand that many people simply don't know how to operate them. That's why I believe that creating a standardized open-source project that multiple governments can directly contribute to and advertise for parents is the way, because at the end of the day, it should be up to the parents to decide these things, and for the government to facility that choice.
Obviously, besides the internet aspect, the tool should have all the bells and whistles that you'd expect from one, but that's not the topic.
EDIT: And yes, some children would find a way, just like they're doing now for the currently implemented ID checks. It's not lost of me that VPNs with free plans suddenly exploded in 4 digits % worth of downloads. A lot of those are tiny people who are smart enough. Or using an app like a game to trick Facial Recognition software.