I tried to review that but its not possible, because the view_template Choice field is required but the default vocabulary only returns one entry with an empty value: https://github.com/plone/plone.app.standardtiles/blob/main/src/plone/app/standardtiles/existingcontent.py#L272 ... should we change this field to required=False instead? If the field is empty, the factory reads the default layout anyways https://github.com/plone/plone.app.standardtiles/blob/main/src/plone/app/standardtiles/existingcontent.py#L177 ...

The result would be that the choice-field has "No Value" and "Default view" and both will have the same effect. That might be confusing.
I'd rather use some default-value and handle that in def content_view_name.

Released as 3.1.4