Newsom should appoint Michelle Steel or Young Kim.
Take a reliable vote from McCarthy, force a special election in a flippable district, force the NRSC to compete in California of all places in 2024 (they would be required to, at the very least, split-match eligible expenditures with Steel's/Kim's campaign), gives him bipartisan cred when he runs for President, plus he still gets to say he appointed a woman of color.
This is a little too galaxy brained for me. Actually a LOT too galaxy brained for me.