I'm not comparing to fossil fuels, so it's not really relevant.
> Or you know, just diversify renewable supply chains?
That's happening about as fast as seawater extraction. There's good reasons why, at least for wind the extraction and processing of rare earths is an environmental catastrophe and only China is willing to pay the environmental price.
Regardless fuel costs for nuclear plants are roughly zero, about $0.0015/kWh, and there is more than enough uranium on land. And of course reprocessing spent fuel is a totally viable solution; most of France's uranium is closed loop. The entirety of the cost is in building and financing, which can be solved with policy changes.