I have enabled 5 Forward Operating Bases (FOBs) for both the Blood Raiders and Guristas pirates for testing on Singularity. We are currently testing functionality of the structure and its reinforcements, and so there are some details/features still remaining to be finalized and are work-in-progress.
Currently they can be found in the following locations:
In order to find these FOBs, you can utilize an expanded probe launcher loaded with combat probes to scan down the structure, and then warp to it.
Pirate reinforcements will spawn if the structure is threatened, in a similar way to the pirate shipyards.
We recommend trying to take these down with some friends.
Should you notice any issues, please create a Bug Report as usual within the EVE client, from inside the Help menu (F12), and then Report Bug.