Would be nice to see a comparison with MySQL's X Protocol (protobuf based) as well as the "Classic" protocol. I don't think I've seen any MySQL compatible databases implement this protocol yet, so that's probably why it wasn't included.
I have vaguely looked into it, but since we don't support it at PlanetScale and unlikely we will, it didn't seem worth it. It'd be hard to construct a practical test.
Similarly, since support is so low, it didn't make a lot of sense to double down and support it when we could do what works for us.
https://dev.mysql.com/doc/dev/mysql-server/latest/page_mysql...