"Approved browser" in this context have technical restrictions on user freedom, e.g. https://developers.cloudflare.com/fundamentals/reference/cry... I'm not talking about someone at CF just adding a random browser to an approved list. More empirically speaking, a browser can't be considered approved if you can freely fork it and not revoke the approved status.
I read the article you referenced, though not very carefully due to lack of time, but I don't see anything like a list of supported browsers. They even mention Firefox as supported, which can be forked just like Ladybird.
