This is a surprisingly late realization, but I can include hyperlinks that point to local files in the test explorer summary window. This way tests that generate image outputs can have a link you can click to launch the image locally.

string localImagePath = @"C:\path\to\your\image.png";
string localImageUrl = new Uri(localImagePath).AbsoluteUri;
TestContext.WriteLine($"Local Image URL: {localImageUrl}");