Thanks to an incompatability between dracut and systemd version 256, I was left with an unbootable system. I booted a live USB system, downgraded systemd back to 255, but I had to regenerate the initramfs images to be compatible with my old systemd.
While using systemd-nspawn is convenient for modifying the system from a live usb, generating dracut initramfs images through it, resulted in missing hardware support (for example, no nvme module) due to the abstracted hardware in the container. The solution is to revert to the traditional chroot and generate the images from there:
$ sudo /usr/lib/systemd/systemd-cryptsetup attach root /dev/nvme0n1p3
$ sudo mount /dev/mapper/root /mnt/
$ sudo mount /dev/nvme0n1p2 /mnt/boot/
$ sudo mount --bind /dev/ /mnt/dev/
$ sudo mount --bind /proc/ /mnt/proc/
$ sudo mount --bind /sys/ /mnt/sys/
$ sudo chroot /mnt/
# dracut -f --regenerate-all