Good post, a lot of good content in there. I almost completely agree with you; globalization, where we can communicate and interact with others all around the world, almost at the push of a button, is an incredible thing, and should be embraced by everyone wholeheartedly. The idea you attribute to globalism (I think "world government" is more accurate, if a bit clunky) is quite bad; it would only further decrease the sovereignty of the individual, making their personal wishes even less meaningful then they are now.
Nationalism is also bad, in general, as it makes people unreasonably disdainful to those of other cultures, religions, and so forth. All human beings deserve the same rights, regardless of where they are born, or any other particular characteristic about them; as long as they do not bring harm to others, everyone should be free to do what they like, practice what values they like, and live in whatever nation they care for.
I want to post more, but my brain's stopped working, so that's it for now. :p
Before I go on preaching individualism, I think it's important to recognize the difference between Globalism and Globalization. In short, Globalism is world domination, the belief that a one-world government should be in humanity's future. Organizations such as the UN and EU are a step in this direction, which is why they have been receiving a lot of well deserved hate. Globalization is simply free trade. Ideally not free trade as so-called free trade agreements have presented it, but free trade in the form of abolishing international barriers to trade, such as tarrifs, sanctions, regulations, and subsidies. I've noticed people getting these confused often, when Libertarians call themselves Globalists, and alt-righters saying they are against Globalization.
Globalism is a plague that we are lucky to be waking up to so early. Despite what you think about Brexit and Donald Trump, the fact that they are a step away from Globalism is important. The only problem is what these events have traded globalism for: a smaller and more ancient evil known as nationalism.
In a libertarian mind, the only difference between Globalism and Nationalism is scale. Either way, people will be forced to live under a regime that has humbly granted itself the right to control their lives and the lives of the people around them. Globalism just does this on a greater scale than any of history's Empires could ever dream of.
The problem Globalism and Nationalism have, and Individualism lacks, is collectivism. Sovereignty should be no greater, and no smaller, than an individual and their property. Forcing individuals living in an arbitrarily defined area to share their sovereignty is a violation of basic rights, no matter if it's done on a small island or the entire planet.
Democracy in the West has naturally lead people to nationalistic tendencies, and I do not say that to the merit of democracy or nationalism. Allowing people to vote on how resorts should be allocated, what people should be forced to do, and how their property should be used has created the illusion that "the people" own the country their government has control over. Nationalists would often, when campaigning against Globalist policy, refer to the nation they live in as "theirs" or "ours". America is owned by Americans, and they therefore have the right, through the use of the state, to violate the property of those non-citizens who live in it.
Given the many destructive disadvantages of modern immigration, and the irritating unreasonable defense of it by the left, this stance is understandable. This does not change the fact that America is not rightfully collectively owned by America. Property owners in America own their property rightfully, regardless of if they violated the state’s laws. Promoting nationalism for these reasons is an unlibertarian stance.
Nationalism is good for only one thing: just like it was to colonial European Empires, it is a wrench to the Globalist machine. After that, it does nothing more than infringe the rights of the individual for the sake of promoting an illusion of collective ownership.