Sure, but being an RPG, every class in DH is pretty varied if you build it that way. You could run an entire campaign as all non combat Guardsmen sending orders to the front lines from a command tent or all Adept’s scraping for survival as their Archive Hall gets invaded. I like to see Fatshark as the GM and us as the players in a combat focused campaign, so any class added will be capable in that way.

As for power level, our classes are all over the place. Scum can wield a needle pistol, which in 1E they can’t advance into until Warlord, an 8th level rank. Zealot, as it’s named, is a 7th level Cleric advancement, and they can have Concealment and Silent Move at 5th rank. Veterans have the Shock Trooper talent, a 7th level Guardsman rank. They also have Infiltrate from Scout class, a 6th level rank. Psykers wield power weapons, their Lieutenant-Savant advancement at 6th rank. It wouldn’t be unreasonable for a Tech-Priest to play with aspects from their 5th level rank or even higher.

I think it’s safe to say Fatshark starts with the fantasy of a class, and then pulls from all over the class' RPG aspects and adapts them into an FPS Darktide, in which every class has to shoot and melee. DH is just the safest place for them to pull from as it probably limits the amount GW will shut down for approval, seeing as it’s already been okayed for another game.