How Imporant Is Fellowship Stat in the Game?
Fellowship governs the social skills of the game and all skills are important to cover, but you shouldn’t be raising fellowship on a character that won’t be using it.
The leader (Officer in release) uses this stat as their primary one for abilities and is the best role for raising it, consequently this also makes the character raising it a good “face” for your party due to the skills it boosts.
You shouldn’t really ever dabble in stats that won’t benefit your class however as you need those in your primary ones, but that’s just general advice, don’t spread yourself thin trying to cover every skill yourself, companions will help you do that.
As a sidenote: A character with the Voidborn origin can, pretty quickly, get a feature that lets them use intelligence instead of fellowship for everything that normally uses fellowship (as long as their intelligence is higher).
So if you want to make a skill monkey main character with high numbers in both Lores and Social skills, you can do that and the fellowship stat will be irrelevant for that character.