I'm not trusting my spatial intuition, but shouldn't a theoretical star tracker for solar system use be able to spot the sun and planets and use them for more p

I'm not trusting my spatial intuition, but shouldn't a theoretical star tracker for solar system use be able to spot the sun and planets and use them for more parallax info? I assume you would need orbital ephemeris info much like we need for GPS satellites. But, given measurements of angles to multiple planets, how well could you estimate your position? Would there a lot of error for your normal vector to the earth's ecliptic plane?