I encourage anyone to study these protocols, they are sometimes a lot more prevalent than one might think. Take the Postgres wire protocol, it's supported by a number of databases out there.
Some years I built a data grepping tool, but didn't want to build a UI around it, so I started looking into the Postgres protocol, so that I could plug in existing tools. Getting the basics right was not that difficult, the docs are pretty clear. https://www.postgresql.org/docs/current/protocol.html
Thanks for mentioning Postgres! I am actually pretty curious about the difference between MySQL and Postgres when it comes to their docs about the protocol. My superficial impression is that the Postgres docs are more thorough, leaving less room for ambiguity (some pages of the MySQL docs seem sloppy in comparison, e.g. those documenting the text encoding of values). I would be interested to read an analysis of the development culture of both projects, based on their docs.
Some years I built a data grepping tool, but didn't want to build a UI around it, so I started looking into the Postgres protocol, so that I could plug in existing tools. Getting the basics right was not that difficult, the docs are pretty clear. https://www.postgresql.org/docs/current/protocol.html