I didn't find any 100% guide for this game (not for the console version either) and I don't have time to do a complete guide with maps and screenshots and achievement lists, but if you are used to 100% games, the game will not be too complicated for you. Most achievement come through completion of the game and most collectibles are easy to find.

The game will take around 8 hours or less to complete to 100%. Some enemy encounters will take some time because you'll need some patience unless you want to repeat the section. If you die, you respawn at the last save. The collectibles you got between the last save and your death will need to be collected again (unless in the meantime the achievement triggered and you don't care about having that collectible but I would not to that, just get all the collectibles you lost because of the death one more time).

There are "side narratives" which are basically some flashbacks / letters related to a particular character. They will get completed kind of automatically while looking for collectibles. The "floating" photographs (which you need the camera to interact with) will trigger some memories and are usually easy to spot, if you look around. Sometimes they are behind objects / furniture so just keep your eyes open.

You can have all the collectibles only after having unlocked all the powers. Some "secret" rooms are accessible only through walking through the walls (for example if a door is locked or if there is no visible door at all...like the area in the attic towards the end of the game). So keep an eye out for all these "wall cracks" that can lead to collectibles. Open all the cupboards and check all the shelves (I am short and some collectibles were not really at my eye height). Extremely important to use your first power (the see/hear power) with your right fist whenever you enter a room, because collectibles will glow yellow. Sometimes you can see the glow even through cupboard doors but I still suggest to open them all because some collectibles are small and you will not notice them unless you open the cupboard.

For the voice locks achievement, just know that I got that achievement BEFORE interacting with every voice lock. I am not sure why, but I got it before interacting with the last voice lock. So just so you know, even if you get the achievement, know that there will be another voice lock to interact with (whicever you are missing).

The "memory palace" is very useful and can be accessed after saving the game: the globe you grip to save the game will have a smaller globe next to it. You can grip that smaller globe and you will be teleported to the collection of memories where they are archived and saved under their own groups. Whatever has a lock on it, hasn't been found yet. If you notice that during playing you are missing some collectibles (in the archive), you can check exactly what memory you are missing.

Some collectibles I found hard to notice: Cassandra's letter number 2, which was on a high shelf in the wardrobe next to the (what I think it is) the coat collection desk in the atrium (before the big cocktail bar room). Another one is in the adjacent room, where the actual bar is (usually there is a guy hanging from that tree structure), in the far corner to the left, there are crates and barrels to move (you need to have that power unlocked), the collectible is on the table. This is also part of the mission to open the bunker door.

You should have all collectibles already when you get down the bunker (you get to the bunker through the story). The first dark room on the right after opening the shelter will have a notes by Rachel: that should be your last collectible. By then you should have already unlocked all narratives and found all random collectibles. If not, check your archive and find that particular note on this very useful website and go to its location

https://whitewolf.fandom.com/wiki/List_of_Afterlife_Collectibles