All of the linked apps look trivial to me. Also, the first one, the UI has no feedback once you click the answer (plus some questions don't really make sense as they have the answer in them). There is more on the website, so there could be something interesting, but I'm having trouble finding it among all the noise. Not saying simple apps have no value. Even simple throwaway UIs can have value, especially if you develop them quickly.

This is not really cool or impressive at all?

I feel like I'm being punked, being told that this "bullish vs bearish flash card" thing and this "here's your user agent, something people have been doing for thirty years" thing, are "cool stuff". This guy seriously needed AI to make those?

I can't gauge the other two since I don't use those things, so maybe they are cool, idk.

A page that outputs your user agent as an example of 'cool stuff built with AI'?

llmslave3 appears to have deliberately picked the least interesting from my HTML+JavaScript tools collection here. This post describes a bunch of much more interesting ones: https://simonwillison.net/2025/Dec/10/html-tools/