In Scentfinder, the core rolling mechanic will be roll-equal-to-or-under-stat to succeed. Ill use the d20 & values are presented as such, but it could easily be converted to use a d100 as one fancies (1/20 being equal to 5/100). Rolls of 1 or 20 won't be natural critical results either, as the system already handles criticals elegantly enough.
How PCs & their stats improve through their progression is often central to a game's feel. It has to match the tone of the game & the supposed power PCs wield over their world.
In Gubat Banwa, PCs are warriors of legend; in Lancer, they're elite mecha pilots; in Trespasser, they're survivors killing not to be killed; in Blackbirds, they're destitues destined to play a role in the fate of the world. I never could be sure what exactly PF1 or 5E PCs were supposed to be; the scale changes a lot throughout leveling, a bit too uncontrolably to my taste.
What I think PF2 is most suited to -- & what I aim to make Scentfinder represent is casting PCs as tangible heroes. Members of the Fellowship of the Ring; powerful Darkest Dungeon II characters; Vermintide's Ubersreik Five. They're supposed to win this fight; they won't be killed by any one of their innumerable enemies. But one wrong move, one overconfident stumble in front of an accursed champion, & they're at death's door. The end of one is a tragedy, moreso as it could spell doom for all.
Here's how I've chosen to represent this.