Here’s my guesses on the backgrounds.
Acolyte: I could see Healer, Inspiring Leader, or Ritual Caster working here.
Charlatan: Actor seems like an obvious choice.
Criminal/Spy: Skulker fits pretty well. Linguist could work for the spy variant specifically. Maybe observant?
Entertainer/Gladiator: Actor fits pretty perfectly here too. Maybe Martial Adept or Weapon Mastery for the Gladiator variant.
Folk Hero: I could see Chef, Inspiring Leader, maybe Tough, maybe Lucky…
Guild Artisan/Merchant: No clue on this one.
Hermit: Healer synergizes with the herbalism kit proficiency. Observant could make sense.
Noble/Knight: Defensive Duelist would fit with the fact that the Noble NPC stat block has the Parry reaction, which is functionally Defensive Duelist.
Outlander: I’m thinking maybe Athlete?
Sage: Keen Mind seems like an obvious choice.
Sailor/Pirate: Tavern Brawler, for sure.
Soldier: Weapon Master or Martial Adept.
Urchin: Not sure. Skulker? Observant?