If you create a pictographic language and get others to use it, Unicode will include your characters. They included Chinese and other pictographic ways of writing, after all.
I don’t think pictographic language is that great. Every picture has cultural associations (just look at the associations with 🍆, 🍑, or 🥺). If you would like to communicate through pictographic symbols representing concepts, there’s a wide range of them that over a billion people use every day, and that is (almost) entirely included in Unicode already.