Here's the thing: Even if I dress up what I am saying as a player my decisions are informed by a series of discrete mechanical options with discrete action economy costs that have limitations not firmly grounded in the ongoing fiction of the game. My descriptions also have no real weight. However I describe my attacks the resolution is the same. There are defined discrete effects.
In my estimation this is definitely not fiction first. Calling it such pretty much renders its weight as a useful way to talk about what we are actually doing. It pretty much makes all play of roleplaying games fiction first if we just say things fancy.
Fiction first gaming is not about saying things fancy. It is about the actual description of what a character does coming from the player thinking about the fiction, deciding what to do in the fiction, us choosing what mechanics apply, the description having actual weight on the resolution, and the resolution rules directly impacting the fiction. It's not just about how we say things, but also about how we decide what to say.
This is how sneaking past in orc encampment works in Fifth Edition. It's how everything works in Blades in the Dark.
Basically I want to talk about how things are different and analyze differences in technique. Let's try an example using two games with similar fiction. Let's imagine our player characters are trying to make their way past an orc encampment.
In Fifth Edition we pretty much know how this goes. The players describe how they go about sneaking past the encampment. Based on their description and what the DM knows about the fiction (size of the encampment, how ready the orcs are, what time of day) they determine it fails, succeeds, or they call for one or more ability checks. Success means they sneak past the orcs. Failure means they discovered.
In Pathfinder 2nd Edition outside of combat time is usually tracked in 10 minute increments much like B/X exploration turns. Characters choose from a range of mutually exclusive, mechanically discrete, defined exploration activities like Search, Avoid Notice, Investigate, and Follow The Expert. Like any roleplaying game characters can try to do something that is not defined in the rules and the GM adjudicates. In this case the Rogue would most likely be Avoiding Notice while everyone else would most likely be Following The Expert.
Here are their effects:
Avoid Notice (Exploration) said:
You attempt a Stealth check to avoid notice while traveling at half speed. If you have the Swift Sneak feat, you can move at full Speed rather than half, but you still can’t use another exploration activity while you do so. If you have the Legendary Sneak feat, you can move at full Speed and use a second exploration activity. If you’re Avoiding Notice at the start of an encounter, you usually roll a Stealth check instead of a Perception check both to determine your initiative and to see if the enemies notice you (based on their Perception DCs, as normal for Sneak, regardless of their initiative check results).
Follow The Expert (Exploration) said:
Choose an ally attempting a recurring skill check while exploring, such as climbing, or performing a different exploration tactic that requires a skill check (like Avoiding Notice). The ally must be at least an expert in that skill and must be willing to provide assistance. While Following the Expert, you match their tactic or attempt similar skill checks. Thanks to your ally’s assistance, you can add your level as a proficiency bonus to the associated skill check, even if you’re untrained. Additionally, you gain a circumstance bonus to your skill check based on your ally’s proficiency (+2 for expert, +3 for master, and +4 for legendary).
How this works in practice is everyone would roll Stealth checks against the Perception DCs (think passive perception) of the orcs to be Unnoticed (they have no idea you are there) by the orcs. Any orc who is Searching would also get to roll a Perception check to notice the PCs if the orc was searching in the right area. If any PC fails then we would go to Initiative and enter Encounter Mode. Everyone would likely get to roll Stealth for Initiative with the result also determining if they were still Unnoticed. They might still be able to get away, but it would take some doing.
Much like combat in 5th Edition players are choosing from a discrete set of mutually exclusive, mechanically defined actions that have discrete effects on the fiction and mechanics of the game. I think it should be obvious that the approach these two games take to sneaking past the orc encampment is demonstrably different. Neither is like better, but the decision making processes and how we go about resolving what happens in the fiction is meaningfully different in the same way that combat and exploration in 5th Edition are meaningfully different.
These distinctions matter to me. Personally for dungeon exploration I prefer a more defined approach that highlights the trade offs the characters are making and the importance of time as a resource. Then again I like B/X exploration turns, reaction rolls, and wandering monster checks.
For other types of play where we are focusing on the here and now instead of potential future dangers I prefer a more fiction first approach.