Build me an Oauth Javascript Flow for AWS / SC-API

We are in the process of integrating Amazon Seller Central with our own application to manage our customers. However, we are struggling with Amazon Login and Seller Central authorizations. We need a development. which contains a PLAIN javascript Oauth flow to connect and authorize and in turn posts to Backend so that It can be identified by our Backend (similar to any FB, Google Oauth implementation). You should have your own developer account which we can authorize and we can create a new sample app in seller central so that you can test. At the end, you are expected to deliver a working JS, implementation documentation (so that any appID & developerID can use it) and tests which prove you have been able to receive a valid and successful response from any API on seller central (ie Inventory, Orders, etc). It is critical that this is implemented in plain vanilla JS (not vue, react, angular nor other frameworks) as we will work with Coldfusion for our back end integration. You are free to use existing JS/SDK's as long as you show and document the complete integration and testing so that we can replicate and use. It is also very important to remember that some Seller Central APIS (because of Individual Information) require a stronger token (not the regular LWS), so the library should be able to request this token (I believe from [login to view URL]) This will be validated against the usage of specific Seller Central APIS such as "getorder" [login to view URL] which require it to view consumer data. Please note that although it is discouraged (as we want to use local server and not cloud services) you are also allowed to setup and use specific AWS services such as Cognito to simplify this project, however implementation must be "stand-alone" (not require our management) and fully documented if you decide to. Tests and documentation should be easily done from any regular POSTMAN setup (which is expected as delivery). PLEASE do not rely on postman AWS for digital signature of headers..This should be part of the Javascript library in case this is needed (it shouldn't as it is Oauth-Flow and not API calls). Please only reach out with specific questions to the project, we won't respond to automated bids and developers that don't have the stack nor understand the ask. - Thank you.