US gun laws are irrelevant, since the legality of using violence in self-defense (note that we aren't even talking about lethal force here!) is applicable to a lot more than guns. And yes, in most countries, it is legal, although certain limits of proportionality etc may be imposed, and there may be a duty to retreat if possible.

But also, US gun laws insofar as they pertain to the use of guns for self-defense aren't as anomalous as many people think they are. There are a few other countries in which it's possible for a regular citizen to get a permit to carry a handgun openly or concealed - Czechia, for example.