Amazon SP-API Oauth Authorization Authentication for Private Desktop App

Assistance needed with Amazon SP-API new private application development. I am registered as a public developer on Developer Central and have registered an a-application that will be using Amazon’s SP-API configuration. If I need a seperate account to accomplish this private instance I can provide that. My integration applications currently moves data to and from Amazon thru the AMTU product that Amazon is retiring. I need to connect using the new SP-API and would like assistance or code written to provide the 'Self Developed' requested in the application registration process. In addition, I would like a piece written in VB.NET to demonstrate how a desktop application can utilize the SP-API authorization and API calls to Amazon. The two API calls I am most interested in completing are Get Orders and Update Inventory but any successful SP-API call would be enough for me to use as a guide moving forward with other calls. An Amazon Sandbox account, developer account and ARN are available and already registered for this project. More information on the type of app I am developing can be understood by reading ‘Developing Desktop Applications in Amazon SP-API’. See: Hybrid applications. Previous experience creating a Public Application for Amazon Sellers is highly desired.

Deliverables for this project includes:
1.) Necessary process to the Grant Authorization described in Amazon’s SP-API documentation for a Hybrid app for a self developed (private) application.

2.) Steps outlined in a text file that a user would follow in order to register and implement a self developed sp-api desktop application.

Preferred technology would be VB.NET (using studio 2015 thru 2022).