Factions which offer many different jobs will offer you also challenges. Making them gives you money, friendships (or conflicts because some of the challenges are aim against other factions) and access to new equipments in stores.
Each challenge has different nature but their rules are usually banal. You will experience many time races - similar to Doom Patrol mission - where you will be forced to reach check points [#173] without wasting time.
Pirate faction specialize in giving challenges. They live on islands in the north-west part of the map. They don't offer any story missions; only taking over outposts and challenges.
Some of the tasks require providing them with cars full of bottles of rum [#174]. You have to be careful then because if you start driving fast you will probably lose some of them.
Challenges are similar to wagers; once you finish a task another level of difficulty will be available (less time, more bottles of rum etc.) - and better money of course..