This looks like it can be a common case that users want to use structs like in this forum question: https://forum.scylladb.com/t/can-we-make-an-enum-serializable-so-it-can-go-to-and-from-a-cqlvalue-in-rust/1242
While I don't see any sensible way to derive for arbitrary enums, we could add support for enums without data.
I think this shouldn't be too hard. The main question is how to specify the type to serialize to (i32, u8 etc)?