Many countries have strict laws how to deal with genocide, genocide support, and genocide deniers! So just enforce local laws, report supporters of genocide to police.
This doesn't seem to even relate to the question. How am I suppose to out the Israeli government to my local police? Or the miriad entities that support it?
Indeed. It has to be a particular kind of recognized genocide, and then people just don't agree on what is and isn't a genocide. Turkey is the worst offender there, but it's quite a widespread problem.
And, of course, the problem is people don't agree. Turkey refuses to accept many of it's actions as genocidal (because that's how Turkey was created: when the last islamic state ("the Ottoman empire") got destroyed by Turks (who at that point were the ottoman army), they massacred a LOT of population groups, famously the Armenians but academics name more than a dozen separate genocides: Greeks, Kurds, Azeri, Jews, ...)
Oh and of course they kept doing it. Technically what Turkey did in Cyprus is also a genocide, and they have an active policy of replacing Kurd population groups but that's, if that's even possible, an even worse sore point.
The sad fact is that these genocides happened to gain territory. And, most of that territory, go look at Google Maps. This was mostly deep inland Turkey. And ... Turks obviously don't want it. There's no big cities there, and the more east you go, the less little towns, the less people, the less everything (except on the border). After the genocides what was a European landscape, a village every 5km or so is now empty. Hundreds of kilometers of nothing. Names on a map , with nothing or ruins below them. You don't really need a line to find the Armenian or Georgian border: where the farms begin, the rectangular fields, the villages, you've crossed the Turkish border. In other words: what repopulation the Turks did ... is a failure. And what little remains, mostly near the black sea, is losing young people at an astonishing rate. This is huge empty space, mostly ecologically destroyed land, not productive farmland. Not nature preserves. Nothing.
Also the reverse also doesn't apply. The UN may have trouble with Israeli actions, but where the UN took control to resolve the situation, where the UN took action, most famously southern Lebanon, it has not just failed but it systematically kept getting worse for 50+ years now. Whereas at least for Israel you can say: look at Tel Aviv. Look at Jerusalem. Look at Haifa. They really built something. Where the UN "helped" ... there's nothing.