This stuff never works. And plenty of sites don't even implement the checks anyway.
I'm all for preventing kids from seeing harmful content, or being on social media at a young age, but these solutions are just plasters on an open wound.
I'm not saying it would be perfect, but it seems to me like routers should come with a QR code sticker on top that, during initial setup, will take you to a parental controls menu. One that should be vastly more idiot-proof than they currently are.
From there, people with kids can decide whether they want it on or not.
Will it prevent everything? Of course not! But it does place control in the parent's hands, makes it much simpler to understand, and doesn't come with data-handling plus privacy quandaries.