There’s literally nothing we’re told about clones that preclude them from still being around or even just a possibility.
Other than that they were once common enough to fight a war over, and nowhere to be found today. Agreed that there’s a chance they may have all collectively decided to do a post-war retreat to Ceti Alpha V and not sign the required release forms allowing them to appear in any films. Same probability as there might really have been a Battle of Wigglypants, or that Vader has a third arm you never see because it’s under his cape. Not mathematically impossible.
Again, it’s a big galaxy. Your “nowhere” is just a handful of planets. And we don’t know if we could really say they were “common enough to fight a war over.” Again, if we’re going just by the original film, all we have is the phrase “Clone Wars.” That’s a completely reasonable assumption to make but it is not the only possibility.
Going back, your Alderaan analogy doesn’t really make sense at all. We know with a 100% certainty that Alderaan was destroyed. A closer analogy would be if they mentioned Dantooine. Even though “it has been deserted for some time,” that doesn’t mean there isn’t the possibility that it can become undeserved. And even that’s pushing it, because we are explicitly told that Dantooine has been deserted, whereas with the clones, any idea that they’ve been out of commission is a complete assumption on your part and neither explicitly confirmed nor definitively denied by anything in the any of the films.
Star Wars has always played with our assumptions. We see pretty much all of Vader so it’d be pretty silly to say he has a third arm, but then again we were told that Vader murdered Luke’s father and that turned out to be not the case at all. If they wanted to they could easily retcon the Tonnika sisters or the multitudes of Greeds or whatever into clones and it’d make just about as much sense as Vader being Luke’s father. My point being, again that it’s a big galaxy and the filmmakers shouldn’t feel beholden to the random assumptions of fans on the internet. If it doesn’t explicitly contradict, who cares?