OpenAI is different: they don’t grant options, but “Units” that are more like RSUs.
Often RSUs in non public companies come with a double trigger: you need both the vest to happen and a liquidity to happen for the actual delivery of those, so no tax implications until a liquidity event (afaik. But don’t take tax advice from randos on the internet).
In the US, equity given as compensation for work could be taxed as wages, or, under certain circumstances, as capital gains.
The one year is for some capital gains to get considered long term gains, which may be taxed at a lower marginal rate than regular wages.
In other words, if you are granted equity as compensation, go talk at length to a tax professional to get an understanding of the taxation of it.