Currently, Reports bot output is based on WikiProjects, as defined in the project index database. This is fine for existing WikiProjects, but increases the burden on our users who want to have short-term collaborations and don't want to invest effort in creating WikiProject assessment categories. There should be an ability to define an arbitrary list of articles, whether in wikiproject.json or somewhere else, and then have reports (such as new discussions) based on that.
This will especially be useful for the Women in Red project, the scope of which is "biographies about women". They could in theory embark on a massive talk page tagging campaign, but why should they have to when they can just say "anything in Category:Women and subcategories" (or something like that) is in scope.