Would not Quinn becoming a jungler fit here theme and lore better?
Just a snippet from here lore:
"Quinn and Valor are an elite ranger team. With crossbow and claw, they undertake their nation's most dangerous missions deep within enemy territory, from swift reconnaissance to lethal strikes. The pair's unbreakable bond is deadly on the battlefield, leaving opponents blind and riddled with arrows long before they realize who they're fighting: not one, but two Demacian legends."
That to me screams jungler and her Kit actually somewhat covers this better than what you would expect and just need that little something to make her viable in the jungle.
Her passive while not the best, procs often on jungle monsters and help her clearing by granting her more dmg and more attack speed and movement when you have W. Not to mention when she sees another champ in the jungle they are more likely to get passive procced on them because there are lack of minions around.
Here Q, is a blind which hits in an AoE making her both a little more tanky when she does have to get hit when kiting monster and helps in clearing speed.
Her W can keep her safe in the jungke and helps when securing objective/buffs which is usually less illuminated than her botlane counterpart because she has a support keeping up the vision.
Her E is a point and click interupt/knockup which means she is able to get on target when she ganks like a pantheon and is usefull when she can easily proc red buff more easily than other champs.
Her ultimate is basically just an empowerment of all her abilties and just strengthen her ganking/dmg/dueling
Honestly I think all they need to do is just add another passive to her W or Passive that gives her some sustain only against jungle monsters or add a onhit effect so she can use devourer more effectively.
I am not saying to buff her so she will be even stronger toplane.
This might be a brainfart and might be a dumb idea, but I just had to share it.