I have written code that implements Avro serialization for POCO classes - i.e. classes that are not generated by Avro codegen and do not implement ISpecificRecord. The idea was to make it work as much like JSON.net as possible.
The serializer inherits from SpecificDefaultWriter and the deserializer from SpecificDefaultReader.
Avro fields are mapped to C# properties either by matching the field name and property name or by using an attribute to specify the field sequence number.
Is this something that would be of interest to the Avro project? My company has approved committing the code and I'd be available and happy to maintain this code and work on other parts of the C# implementation.