I've noticed that Seons and Spren are very, very similar but i haven't seen anything like that in the Mistborn world.
In Mistborn the Investiture took other forms. It never obtained sapience in the same way. Its theoretically possible that it could have but it.. yeah.
So it wouldn't be like the Mist?
Yeah, you could say that the Mist has a bit of sentience to it, so yes, but there are a bunch of different things going on. On one hand, you've got, right up to the end, Preservation's Cognitive Shadow still around doing stuff, basically still there, so that's preventing it. It's just a very different situation.