Do you think it’s worth the money to hire a mercenary until you get enough story companions to fill the party? Like, does it take a long time to find a full roster? Or perhaps it’s like Pillars of Eternity, where the early game is challenging enough that hitting one or two is very helpful even though it’s not _too_ long until you have a full amount (and later those mercenaries can help out at your castle anyway)
Definitely worth it. There is not enough gold in the game, this is a fact, so you will have to steal from merchants to correct this injustice (especially from those in random events). Most companions (except Embla) do not play a big role in the adventure, so they can safely be replaced by mercenaries.
The dude is an officer class. They aren't meant to be strong fighters, they are meant to buff party members during fights. Likely sit closer to the back occasionally doing a little damage here and there while they buff your other party members during the fight.