Where did I say that I don't think of people in other countries as people? That's quite an extreme suggestion.
Not really.
If you think of everyone in the world as people, then nationalism very obviously unites some and divides others. Someone who believed that people in, say, China were people would not say what you said. It wouldn't even occur to them.
But if nationalism only unites people, then all those other "things" that it divides them against must not be people. That makes perfect sense, but
only if you don't think of the Chinese as people.
You don't have to say it out loud to make it very clear that you don't think of the Chinese as people. You're going to backpedal on it now, but your inner beliefs came through loud and clear with what you said.
But honestly, how would YOU unite the people of America against the rise of tyranny?
Well, the call is coming from inside the house at this point so that's a bit of a big ask. The people of America demonstrably want tyranny - they elected a tyrant who publically campaigned on his promises to act tyrannically. I'm not sure it's in anyone's power to unite people against their own wishes.
But let's generalise and say that you have a lot of individuals who are against tyranny, but just need to be united to form a strong coalition against it. How could you go about it?
You can show them that there are other people that feel the same way and give them ways to meet up. You can start leading and organising, even at a fairly small and local level, because this may grow into a greater movement. You can make sure to visibly support people who have been publically injured by the tyrants to encourage others to resist. You can make public the damage that the tyrants are doing to individuals, to communities, to everyone within their reach.
Hell, you can start a militia to enact violent resistance and assassinations if you really want. Or just get a weapon and go full Saint Luigi hoping that other people will follow your example.
There's lots of ways that you can unite, basically anything that makes resistance to tyranny visible and encourages others to join in. None of this requires reference to any nation at all. You are simply a group of people who are against the behaviour of the tyrants and are willing to act in resistance in whatever form that takes. That is the bond that links you, and that is enough. For the people where that isn't enough to draw them into the group, they shouldn't be there anyway because they're not actually against tyranny.
Throwing in nationalism doesn't help this, it just gives ways for the movement to mistakenly target individuals or groups that the national identity labels as
"other" and avoid targeting those labelled as
"citizens". Those are not the groups that are the problem if your purpose is to fight tyranny. You want to target
"tyrants" and avoid targeting
"non-tyrants", and those groups can be external or internal.
Know your enemy, because I don't think you do. You're just parroting more stuff that you've been fed on the internet without really thinking about what it means. Maybe this time sit down and have a think about what you actually believe before you go off half-cocked.