Hi Giuseppe,
I'm not familiar with OData myself, but according to some Microsoft documentation, the functionality is provided via a Nuget package, meaning it will work on SnapDevelop without a hitch. You would have to set it up by yourself though, as there's not a OData project template.
As for using .NET DataStore, it makes sense if you're trying to consume the API services from PowerBuilder, otherwise you might be better off using SqlModelMapper which complies more closely with C# standards and as such, it might be easier to work with for a C# developer
Regards,
Francisco