Long story short: finished main story at launch, bought the season pass on this last sale, updated the game and got random crashes, but not long after opening game.
After A LOT of research, decided to Reset my overclocks on Afterburner and voila.

Been playing for a few hours already without a crash.
I hope this keeps working, but from what I tested before, this was the reason for my crashes.

Yeah, after my post yesterday, I came back to the pc and got crashes again.
Googled a bit more, found the windows clock fix (just sync it), didn't really work.
Read somewhere that overclocking your gpu might make the game unstable.

Remembered one thing: when I did the clean install after the DDU wipe, Afterburner didn't jump into action after the restart because there were no nVidia drivers in action. It was open, but couldn't read anything from the GPU until I restarted it after installing the drivers. Thing is: I was able to play the game for an hour before restarting Afterburner.

Today, I killed the OCs on it (clicked the Reset button to stock settings) and am playing the game for more than an hour already.
I'm yet too afraid to call this a victory, but this is improvement on my end: killing the overclocks on my GPU makes the game stable enough to play it.

I will post this on a proper thread so it may attract more views and possible help others.

@ubi-mark No luck, crashes came back.
I'm still testing stuff tho. Gotta do some work now but I plan on testing a bit more later. Will keep posting updates.

Last thing I tested was killing all my OCs on Afterburner. Game opened, loaded my save and was able to run around for a bit. Will try to play more later.

Some news:
I played all of Odyssey and vanilla Valhalla on this rig (8700 + 2080S + 16gb ram + nvme ssd).
As per my other replies, I'm having my gameplay harmed after purchasing the Season Pass.
Today I decided to do a clean install of my drivers, did a DDU uninstall, installed 471.68 drivers. This plus UbiConnect on offline mode are making be able to play the game for a while, just had an hour long session but I gotta do some errands now and closed the game.

Will update this later.

Too soon. Crashes came back just as they did before. Can't pass the splash/loading screen.

@hot-single-dad Thanks for this. It seems like this is helping me! I'm still testing, but I was able to finish a raid on Ireland. Gonna try and play a bit more and update it here.
Thanks again.

@longjohn119 Thanks for the reply.
Yeah, no luck, sadly.

I've tried changing all the TobiETCEnabled to 0 aswell but no luck.
My crashes are entirely random, sometimes on the splash screen, sometimes I get to load the game, sometimes when browsing the options menus. I can't see a pattern.

@ubi-orion @longjohn119 Yeah, no dice.
My ACValhalla.ini didn't have this option, so I inserted it, saved and tried to give it a try. Still crashed on the opening screen, like it did before.
@longjohn119 would you mind sharing your .ini content?

@longjohn119 I replied there.

@longjohn119 Is this ini on the Documents\Assassin's Creed Valhalla folder?

Game is unplayable for me. Wish I could refund but this is happening after I've got the Season Pass on this sale.
Hopefully a 1.3.2 or 1.4 update comes soon to fix this.

I played this game for 70+ hours I think, had maybe 5 crashes, nothing worrying.
Bought the Season Pass last week, updated my game and now I simply cannot play it. I have crashes seconds after the loading screen (I don't mean the Continue button, I mean after the Ubi logo).

I've done a myriad of things to test, tweaked a lot of things: Nothing works permanently. I play a bunch of other games on this PC without issues (Apex Legends on a daily basis).