Booting with a live iso and tried everything (lsblk, blkid, fdisk, parted, /proc/mounts, and /etc/fstab), the NVME drive is not shown (as if it did not exist) by any method.
I could copy the outputs here, but there is no point, as it is very clear the drive is not detected.
Since it is not detected, all solutions with mounting methods i found online look useless, as I would not be able to manually mount / fsuck / chroot a drive that is a total ghost.
I sought professional assistance. They were able to recover all the data with some specific software. The NVMe drive is in good health, and I am using it as an external drive with an USB-C enclosure now. Still cant boot with it. The internal NVMe was replaced and after a fresh install, everything is working fine. I had the dotfiles saved on Dropbox, so setup was smooth. Thanks, everyone.