As the topic asks. I am wondering if it is possible to use tags to populate a Collection Project. That is to say, only observations with a selected tag would be included in a project and adding that tag to your observation would be what adds it to the project. For instance a tag such as “redzoom” causes the observation to be included in the project titled 680 (currently fictional). Project observations would not be based on taxon or location. Others would know or find out that adding this tag would include their observation in the project.
Don’t know about traditional projects, but on collection projects, neither tags nor fields nor annotations seem to be selection options. There have been a couple of related forum topics, but no feature request that I can find yet specifically to add any or all of these options for collection project criteria, so you might consider submitting one. The related posts: