The 25th amendment is designated to the presidency, not the VP. Jill is treading on dangerous territory here, Kamala is duly elected, Jill isn’t .
Like in House of Cards, you get the VP to resign then choose your wife to become the nominee for VP. Confirmation required, of course, unless maybe Brandon will sign an executive order MAKING Jill VP.
Why not? He makes all kinds of illegal executive orders all the time. What’s one more?
After becoming VP, Unlike in House Of Cards, where the president is murdered, Jill gets the cabinet to invoke the 25th amendment against Joe and voila! Jill is president. “Officially” although she has been “acting” president for some time now.