I think millions of Americans believe it is either conduct a successful Article 5 convention or the US breaks up into a number of different countries or unions of states.
If we break up, other nations will not just stand by and watch.
As you postulate, we must conduct a successful Article V series of conventions.
Right and it is what some call a “false dichotomy”, a false choice.
The real answer is individual states standing up for their constitutional sovereignty and saying “NO” to and nullifying federal tyranny. It’s saying “We the states AND you the feds are under the Constitution. We the states are sovereign outside constitutional restraints and you, the feds, will get cut down to constitutional size and remain in your constitutional cage.”
Secession isn’t the first step, it is the last step if all else fails. There is much that can be done before the drastic step of secession is made.