As someone who likes sniper rifles, I would LOVE a 1 hit kill, but as a player against snipers, I do not want a 1hk, and with 127 enemy players, I do not want a 1hk in the body.
The reason games like Squad and such have a 1 hit kill sniper is because of limits, map size, and game play style.
Squad is built as a more realistic shooter, not an arcade shooter.
I find myself just taking multiple shots or aiming for the head only. I avg about 50 kills a match with a sniper rifle. Which doesnt seem like a lot, but when you add the range bonus, headshot bonus, OBJ bonus, your score can and will rapidly climb.
Just your idea will not fit into the game with the games current playstyle.