How to customize the viewer for files in Autodesk-construction-cloud

When I click on a file in Docs or Build within Autodesk Construction Cloud, the file is displayed on the web (viewer).

help.autodesk.com/view/DOCS/ENU/?guid=View_Navigation_Toolbars

I want to customize this viewer.
However, I couldn’t find a way to customize it using the APS viewer API.
Is it not possible to customize it?

If customization is not possible, I think I will have to create my own web page and use the viewer API there.
In that case, when I click on a file in ACC, I need it to jump to my own website instead of the above viewer.
I understand that this is impossible.
(This text is machine translated.)