Recently, I had the opportunity to test a great C# library that significantly improves the development of an SDK.
In later experiences develop an sdk project was something really honorous, wee need to create a lot of classes and methods to handle with the api request and response. Then, during my researchs I found Refit.
Refit is an rest library that helps a lot during an sdk develpment, you just need to create the contract classes (if you already has in an side project is even easyer), and create the interfaces for each controller. Simple as that.