Shameless plug:
When 3.7 was first released, I created a library to use dataclasses and add some light type validation to them. The library grew and now also supports some basic serialization mapping.
I'd love some feedback/issues/PRs
Also related to that I just came across a library that can generate json schema from a dataclass https://github.com/s-knibbs/dataclasses-jsonschema
There's also https://github.com/Fatal1ty/mashumaro for json serialization.