When I was in junior high, my friends and I could write in Tolkien’s basic elf-runes.
I particularly enjoyed learning a version of shorthand. It’s an amazing speedup of note-taking, but it is designed to make written notes of verbal sounds; spelling is tossed aside!
On the other hand, it should be relatively easy to use (shorthand) written notes with an electronic device to be able to read back those notes through an (artificial) voice.
Our friend Charles Schulz, creator of the Peanuts comic strip, often used shorthand notes on his panels to indicate “secretarial” skills in action. They were accurate and amusing!