What if I don't want my nation in the UN? Is there any organization for non-aligned nations to join aside from our regions?
Sure. The Meritocracy, the OSN, various other RP alliances and organizations, that may or may not be connected to other regions.
Other organizations? There are more on here than I even want to count.
If you don't join, you keep your national sovereignity, may make decisions for yourself, and don't have nations out to get you just because you are in the UN. If you join, you are subject to the will of the majority, have all of the disadvantages above, and are part of the only organization written into game rules.