Oprah's not a California resident, so if you want a vehicle for Republicans+Manchin/Sinema refusing to seat her, you have it.
Does she have to be? I thought she was.
That said, I doubt she would only be appointed as caretaker till DiFi's term expires. If - and I have my doubts - she would have to run for a full term. That's why I'm relatively certain Newsom would only appoint a placeholder.
I thought Oprah lived in Alpine, New Jersey, but Wikipedia thinks she lives in Montecito, California.
Would be a ridiculous choice either way.