I prefer extending the invitation to secede on a county by county basis.
It could even be extended to counties in Canada and Mexico, since we are forming a new country.
We could have a referendum on which counties decide where they wanna be, for 4 or 5 decades. Then the borders are sealed.
We already have sovereign enclave nations operating in the United States -- they are called Injun Reservations.
The titles to Indian reservation lands are held by the U.S. government, and the tribes are little more than wards of the government.
You don’t secede you expulse the other guy. You eject the blue staters and the blue mayors both at the federal and the state levels. Of course this should have been done when Trump had a Repub Congress... but it still can be done by calling a rump Congress and invalidating Biden.