I doubt any monarchy would survive if the people had the physical means to resist it. Monarchy = tyranny.
The monarchy that was overthrown here was actually a democratic one. Similar to England with a monarch but a fully empowered congress that represents the people and does the heavy lifting. While there is most certainly tyranny in Hawaii's past the government that was overthrown was among the most egalitarian in the world. Complete with the corporate interests buying of the legislature that everyone else has enjoyed since the dawn of "representative" government.
But bass monkey nailed it. Which of the 30+ "Hawaiian Kingdoms" is this? Oh, who cares. Since there is no unity about sovereignty it is ~highly~ unlikely to happen even if there is a legal and moral case for it.
The sovereignty folks should really have a heart to heart conversation with the Native Americans about the success of their legal and moral arguments with the United States over the years. Yeah, the UN has ruled against the US. So? It has also ruled against the US regarding the Native Americans. Repeatedly and without effect. Just because it is (gasp!) true that the US took Hawaii (and the rest of its land) by force or trickery doesn't mean anything is going to change. Its not some huge, vast conspiracy to break laws... its the way nations have behaved since the very first nation. Its only been since WWII and the artificial fixing of borders that happened afterwards that the illusion of stable political boundaries has seemed real. Doesn't make it "right" or "moral" but it has been business as usual for... oh, about 5000 years that we have written records of. One might suggest at some point that getting over it would be more fruitful than trying to change it.
As to the topic... theoretically a Hawaiian Kingdom could have different firearms rights for its citizens. The chances of them being much different are fairly slim as the culture here is what it is. None of the previous Hawaiian constitutions have any protections of firearms ownership at all. None. Zip. Zero.
The United States is unique with the 2nd Amendment protections of arms ownership without required military service. Regardless of the various state and federal laws that restrict gun ownership in various ways we still have more access to more kinds or legal firearms than just about anywhere in the world.