While this may be a really dumb question, I just want to make sure before I try to SOS chain for one. (btw I cant find the answer to this question anywhere else)
No. You cannot get starters Pokemon as wild. (You can get starters from island scan). But you can't SOS chain Pokemon from island scan. So the only way to get shiny starter is Masuda Method, Soft reset and Pokebank.
No, you can't.