From GameWatcher: “Far Cry New Dawn has got the most substantial selection of companions we’ve yet seen in contemporary Far Cry offerings, short of maybe Far Cry 2, though there was no practical difference between companion characters there.
Far Cry New Dawn companion upgrades are a crucial feature of the game’s roster of support characters, too, and you might find yourself in a pickle at later stages of the game if your crew doesn’t attain a level-up or two along the way.”
Source: N4G PC Far Cry New Dawn – How to Upgrade Companions?