Evolved forms can't be found shiny anyways, only base forms.
The only sorta exceptions are Pikachu (franchise mascot gets to be the exception to everything) and Roselia (since its shiny form came out before Budew was released), and a couple specifically temporary ones (Nidorina/Nidoqueen for like two days for an event, Gengar for its raid day).
Kinda silly, but yeah, don't throw passes at evolved forms if you're looking for shinies. Gotta get the base stage shiny then evolve it.
They 100% can't be gotten from raids? So like a Muk raid would be pointless? ---