How to add a photo to an app shortcut IN THE SHORTCUTS APP

I have created an app shortcut in the shortcuts app. But, as far as I can tell, when I click on Choose Icon, I can only select a color and/or one of the glyphs that are available there. It doesn't let me open my Photos app and select a photo to use. I know I can add a photo to the app icon after I add it to the home screen, and I have accomplished that. The problem is that I want to share my app icon with others, and I want the app icon photo to be included as part of the icon shortcut in the email that I send. I know that I can export the shortcut as a file from the Shortcuts app (it generates a .shortcut file and includes it as an attachment to the email). But that .shortcut file doesn't contain the photo, because the shortcut within the Shortcut app doesn't contain a photo. And while the shortcut on the home screen does contain the photo, there's no way I can see to export that. I know I could also send people the photo separately and give them instruction on how to add it to their home screen shortcut, but my users are not computer savvy at all and I'm trying to make things as easy for them as possible. So: Is there a way to add a photo to a shortcut within the Shortcuts app, or is there a way to export an app icon from the home screen (that contains a photo)? Thanks very much!