In a configurable application, how to get the configured parameters using jsApi 4.x?

I'm using:

<script src="./lib/arcgis.dojo-4.6.js"></script>

and

<link rel="stylesheet" href="https://esri.github.io/calcite-maps/dist/css/calcite-maps-arcgis-4.x.min-v0.6.css">

<link rel="stylesheet" href="https://js.arcgis.com/4.6/esri/css/main.css">

My code is at:

GitHub - Horiatu/ReactMapViewer: Tests on a Map Viewer with React 

and runs at:

React Map Viewer 

(My first attempt is in the file ./js/templateConfig.js but currently not included in the application.)