Vice Presidents don't resign. Only two have. Spiro Agnew because he was tax crook (no contest for tax fraud) and John C. Calhoun. Calhoun did do it because of political differences with Andrew Jackson - but that was in 1832.
Just my view, but were Vance to resign, that would cause chaos in the party, pretty much guaranteeing a democrat wave in 28.
With respect to some coherent leadership from Trump, that would indeed be a Godsend. On tariffs alone, even friendly press like Fox is bewildered. He also has a counter productive way of pronouncing what a situation should be (in his mind) such as Ukraine, China, Venezuela, Greenland, etc without the means to bring his desires to fruition. To the voters, that has a way of looking like failure. Finally, the whole national guard thing, however effective in restoring order in a few places or in helping round up illegals, represents really bad optics for many - particularly independents.