You read that right, Bethesda has commissioned a Dark Rum to be sold as Nuka Dark rum. There is a limited supply, but the 750ml of 70 proof bottles aren't cheap at $79.99.
You can find them through the NukaDarkRum.com site, but a warning, you will need to confirm your are 21 to enter. Expected shipping date is 11/14/18, so if you want this, likely, limited collectible with a nice side benefit, order quickly.