IIRC, Graffiti itself used to be patent-encumbered in the 1990s, but any such patents should be fully expired by now. I wonder what's blocking a FLOSS reimplementation of something similar for the modern mobile platforms. If the glyph shapes are problematic (though they shouldn't be) there's also https://en.wikipedia.org/wiki/Moon_type which is over 100 years old.
Historically, graffiti-like systems have also been used for "night writing", so they might have some accessibility benefits as well.
Historically, graffiti-like systems have also been used for "night writing", so they might have some accessibility benefits as well.