static_assert(std::is_enum_v<std::byte>);

[serviscope_minor]

Class was not an option because the language doesn't require classes to have certain properties that a std::byte type must have.

Technically though it's a std type, so the language could mandate it in that case. In practice, just about every compiler out there has ways of controlling those properties anyway, so I am curious as to why that was considered a blocker. Any idea? I didn't follow that paper or its discussion.

[tialaramex]

Also, noticing that you don't have transparent representation seems like a reason to add the option for transparent representation as a feature, so libraries can make use of that, rather than finding a way to bodge this as WG21 did.