The difficulty with serialization formats is that you're serializing for a reason. What if I want to read these dataframes into C++ or Python or some other lang

The difficulty with serialization formats is that you're serializing for a reason. What if I want to read these dataframes into C++ or Python or some other language? It's pretty rare for pure performance to be the only consideration in choosing a serialization format - and unfortunately all the other reasons favour well-supported, long-established projects that can afford to hand out libraries in every language you could want.