I'd be here for them as well, both of them make great pop music. Bonnie has expressed her love for Gaga, not sure about Sia though, anyone got any receipts? I have a horrible feeling Sia would probably loathe her.
She should definitely open up to working with well known producers and songwriters, it can be great even if she doesn't release anything she does with them. It might help her to see how other people work and how their method differs from hers. Just a thought.