You're right. They did. And none, at any point, showed any sign of resistance. I concede the mere presence of guns isn't a deterrence. The presumption of resistance is also required. But merely a presumption of resistance without arms is easily brushed off.
The natives had some guns, yes. But they in large part conceded land, accepted treaties, and many more were under the assumption that they would be compensated for land lost. Some were given this luxury, most were not. Some did wish to stay and fight, but were largely outnumbered, especially by Chiefs that favored a peaceful approach. The US played this presumption wholeheartedly. Especially with information and communication as primitive as it was, the government used this nearly the entire campaign.
The Japanese, again, showed very little to any resistance. But to specifically address this (constantly debunked) claim that simply having more advanced tech/more guns is all you need to nullify resistance, I highly suggest you open a book on guerrilla warfare. Not to mention the whole "a dictatorship wouldn't be rolling over entire cities with drones" argument, that suggests unless a dictator wants to rule over ash, they will use armed police that will be required to go door-to-door, constantly putting themselves on lesser footing than the resident that is presumably armed.
if the japanese people decided to resist the US government if the japanese people decided to resist the US government
Yes, and they likely would have killed thousands to tens of thousands of US troops in the process, especially during a time that we were literally at war with the country many of them or their family came from. Acting like this is at all relevant to the second amendment and not an entirely different discussion on propaganda and segregation at a time of war is disingenuous.
If you think your little firearms would save you from a government trying to oppress or kill you think again.
Refer to above. If you think drones and tanks are at all relevant unless you plan on ruling over a literal scorched earth, think again.
Ignoring that the military is pledged to the constitution before the president and would likely stage a coup if told to violate said consistution, what would be far more likely is the police and national guard would raid homes looking to disarm or kill those with guns. In which case, even with superior arms, you are always entering an unknown area with the defense having a home field advantage.
Guerrilla warfare is considered among the most effective military tactic in the world for a reason. Especially in the modern age of information, trying to suppress a population of gun owners would lead to a decades-long internal conflict that would be effectively unwinnable and would only skew the population progressively more against you as you try more and more desperate attacks that end up killing more and more innocents.
If you want to combat a tyrannical government you need at least some of the weapons they have
Demonstrably false. If you have a gun or the ability to put together homemade devices, you're on all the footing you need to do damage. See: War on Terror, Vietnam War, WWII Resistance from virtually anywhere, etc..