Alright, so this theory of jolly 4 will cover some massive stuff, which will leave you thinking about it for a while (probably)

Cutscenes:

Service cutscene: i think this cutscene will happen in present time, probably something about the animatronics being created, also this will probably happen in route 1.

Silence 1: i think this will have something to do with the post shift tasks and a certain screenshot of Tal, maybe once you go somewhere in the place to do a task, you'll get a cutscene of Tal taunting you before the task minigame begins, idk which route tbh maybe route 3.

Night out: I think this cutscene will begin after you beat night 1, you get out of the place after completing your shift and you'll probably get info on the protagonist's backstory and the jolly 3 facyory collapse, (you will see this cutscene no matter which route because the choice didn't happen yet)

Slender figure: Weshek has confirmed this cutscene ha 10% to do with Tal, so maybe this will have something to do with all animatronics or maybe even the duo, route 3.

The couple: alright this will get interesting, i think someone will tell us more about Liam and Tony (the couple) the "thing" that's telling us this is someone who knows very well about Liam and Tony, someone who was present and made a cameo on jolly 3 chapter 2 (although where it appears is non-canon now.) this will happen in route 2

Silence 2: Same thing as silence 1 but this time another animatronic is present (route 1)

Weshek confirmed the game will have 3 routes depending on the player's choices, here's my theories on what is each one aswell as it's respective ending.

Route 1: This route is the most simple, after beating night one and You will get 3 choices.

1: Stay in ground floor (don't investigate the other floors)

2:Explore the underground floors (go down the elevator)

3:explore the upper floors (go up the elevator)

on route 1 you will stay in the ground floor, this will lead to a very simple route with nothing much going on, not many lore reveals or anything, you will have 2 cutscenes on this route "service" and "silence 2" the ending for this route will be the animatronics getting shipped and another restaurant opens.

Route 2: when you complete night 1, choose to go up the elevator, this will lead you to other floors and "the attic" you will get to see the solo on this route, anyways, after you go up the elevator you will get stuck in floors 2, 3 and attic, you will not be able to exit the facility because of this, you will get "the couple" cutscene on this route, the ending involves you being trapped on floors 2,3 and the attic because of the elevator breaking down you will not be able to go down to the ground floor and thus, you die alone from starvation, this is also rge "depressing route" Weshek mentioned, although it will reveal the most lore out of the 3.

Route 3: when you complete night 1 choose to go down, you will meet the duo on this route. you will also get "silence 1" and you will also get "slender figure" cutscenes, this route like route 1 will be more gameplay instead of story/lore, like route 2 you will also get trapped but instead you get trapped underground, the ending will involve you passing out because of hunger, before you pass out you see a silouete of 2 people on the distance, you get rescued just in time, in the hospital you get to see the 2 people who were employees of jolly entertainment and found you after they went to check the duo's stability, in the hospital bed you see in the news broadcast that the place got closed after they discovered you in a horrible state underground.

ok, this is getting way too long, now what i think will be the solo's identity.

The solo is none other than:

Zoey, aka golden freddy

i can already see many people getting angry and confused, but look, from what i've seen on the jolly wiki,

the color "ivory white and almond" could be referring to Zoey's color pallete in the minigames

The solo was present in jolly 3 chapter 2, you see Zoey in the very last "good ending" minigame (even if it's not canon"

The solo isn't directly hostile, meaning it could be like antonette in chapter 1, which becomes hostile and jumpscares the player.

The solo has an "o" near the middle "Zoey"

since we've never seen or heard of golden freddy on the jolly lore, it very well could be them, also because Zoey was the 5th girl to be killed by william afton (as evident by the jolly 3 chapter 1 minigames)

We didn't get any confirmation of golden freddy being built by either jolly entertainment or fazbear ent.

The animal the solo represents is seen in the fnaf games.

at the same time you see the solo you see a house, this could be reffering to the place in the last good ending minigame, that very well could be a house.

"the place the solo can be seen is on a screen", at the end of the good ending there's a screen showing Zoey, antonnete (Tony) and Liam (W. Jolly)

also since the good ending of jolly 3 chapter 2 isn't canon, that means that Tony, Liam nor Zoey passed on, nor did them get reunited.

MY GOD this was a LOT of typing, i spent like half an hour writing.

Edit: also to be clear, i didn't put anything about the protagonist because i really have no idea who it could be, it could be Theo, Jack, even chief investigator. it could be anyone really.

Anyways, thats it, let me know what you think of my theory, im really looking forward to jolly 4 as i can tell, it will be one of the most fun fangames in terms of gameplay and it will be the most original fangame (maybe?) Atleast it will be more original than most fangames and the fangame i'm making, Anyways thanks for reading this theory, and have a goodtime.