Can the ArcGIS JS API be used to create custom widgets for integration into my local ArcGIS Portal? I went through the Recenter widget exercise, and then attempted to discover a method of integrating that widget into my organization's locally-hosted ArcGIS Portal Web App Builder (WAB). The JS API, as leveraged using TypeScript, Node.js, and npm, does not provide a manifest.json file, nor does it package the CSS, NLS, or other specific items that appear to be necessary for registration with ArcGIS Portal. I'm aware of WAB Developer Edition, but we do not yet have that installed as it takes time to clear new software through our security procedures.
I also do not wish to re-create my own version of Portal using the ArcGIS JS API, as that seems highly inefficient and redundant.
I'm using ArcGIS 10.6, ArcGIS JS API 4.11, and Node.js 8.11.0, on Windows 10 x64.
Any input would be greatly appreciated. Thanks!