Brits want something roughly akin to the online safety act - they want liability for online unsafety. I doubt many of them care about the requirement for platforms to register or the fees for doing so, and would still support it if that wasn't in there.

We should be trying to give people what they want in the best possible way. Otherwise, other people (with ulterior motives) will give it to them in the worst possible way.

For kid's online safety, it would be sufficient for each device to ask upon installation if it's for an adult or a kid, and send that as an HTTP header to each website. We should recommend that, so we don't get a much worse solution to the very real problem - such as UKOSA.