apt install cryptsetup lvm2
unlock the drive with disk tool bc i cant work out how tu use cryptsetup
make lvm visible
vgchange -ay
// mount root
mount /dev/{vol-group}/root /mnt
// mount boot
mount /dev/sdX2 /mnt/boot
// mount all the things
for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
sudo chroot /mnt
// maybe boot/efi can be done before the chroot... not sure
mount /dev/sdX1 /boot/efi
apt-get install --reinstall grub-efi
grub-install /dev/sdX
... and should be good to reboot
mostly from https://wiki.debian.org/GrubEFIReinstall#Reinstalling_grub-efi_on_your_hard_drive