Question

Can I load a local HTML file (with images and …) into a WebView?
Just setting the Source parameter does not do the trick.

Answer 1

You can load it from a file as long as the file is part of the app package, e.g.:

WebView2.Source = new Uri("ms-appx-web:///assets/text.html");

From WebView.Navigate

WebView can load content from the application’s package using
ms-appx-web://, from the network using http/https, or from a string
using NavigateToString. It cannot load content from the application’s
data storage. To access the intranet, the corresponding capability
must be turned on in the application manifest.

For a ‘random’ file, I suppose you could prompt user via file picker to select the file then read it into a string and use NavigateToString, but the user experience there may be a bit odd depending on what you’re trying to accomplish.