Possible to Have Multiple Fixed Items (List) Per Column For Entry to Individual Cell?

Hello, I am trying to have a column which has a fixed universe of non-numerical data-items for entry similar to a list (e.g., Blue, Red, Orange, Purple), but I would like the option of having multiple potential entries from this list for a particular individual cell, so I don't think the list function would work here (i.e., almost looking for a tag-word type function, where Excel would auto-fill an item, and the user could continue to enter additional items after the tag-word is filled).

To make things more complicated, I would like to be able to use the frequency functionality to take data entered into this column and report out on another area of the spreadsheet - so I guess Excel would need to comprehend that each of these fixed items are distinct and independent for that purpose, even if grouped together on a cell (i.e., it would defeat the purpose if a cell under this column contained Blue; Red, and for the frequency functionality, Excel listed "Blue; Red" as a separately tracked item from the Blue item and the Red item).