As title says, my laptop is literally unusable.
My entire screen is ruined, starting from the booting screen up to the login on os. Even going in BIOS is ruined.
If this is the case then it's likely a hardware defect, either the gpu or display is dead. Did you try to use a hdmi cable and plug it in a tv to see what happens ?
Plugging in an external screen somehow fixed it (it came back at the next restart though).
After some more trial and error I'm starting to think it's most likely related to the integrated graphics, because the second screen (which runs on the dedicated one) has literally no issue; only that everything freezes when the main screen is glitched
Huh... I had the same thing happen on a Dell Inspiron N7110 (running Windows) about the same time as you... it only had ~3 lines (like you show in your image) at top of screen, and the bottom of the screen below the taskbar was likewise unusable, but the rest of the screen was OK.
It's a hardware problem... I wasn't doing anything at the time it occurred, and I never closed the lid on that laptop, so it can't be a cabling problem. I'm betting the screen itself is going bad.
Otherwise, the laptop is still usable, so I bought a new one and gave that one to the kids. They're using it with Zorin OS now. When the screen entirely fails, I'll replace the screen... it's not really difficult to do for laptops, I've done it a few times for other people.
This could be a failing cable (the monitor on laptops are connected by a ribbon cable)... if it was dropped or opened recently the cable may be loose...a failing video card (depending on use could go prior to the monitor)... or a failing screen. I've seen this on bad cables, but usually desktop, not laptop.
Does this happen during boot? Does the post (power on self test) display the same? Unsupported resolution and frequencies (60hz, 90hz, 120hz) can have a similar effect. Just cause your monitor can handle certain resolutions and frequencies doesn't mean the video card can. That's why I asked you to boot from the live image (maybe once with nvidia drivers and once without).
Switching the nvidia profile to performance doesn't allow integrated graphics to be utilized. You can perform the switch by gui, app menu -> utilities -> nvidia server settings -> prime tab... choose performance mode. This may resolve your issue (and give you a few more years with the laptop).