So it’s canon that there are more signs than ones given in the extended zodiac??

Trolls sharing symbols is rare. Alternia is a god damn planet. Rustbloods seem exterminated by the hundreds but still exist as one of the most plentiful castes. That alone pretty much confirms there’s gotta be several thousand Rust Signs alone. It’s possible there’s less the more you go up the Hemospectrum, but with an intergalactic empire, the Sign Count pretty much HAS to be on the Billions.