Can you do this after a fresh boot from USB:
sudo cryptsetup open /dev/nvme0n1p2 encrypted
sudo mount /dev/mapper/encrypted /mnt
ls -alR /mnt/boot
It works!
I reinstalled all the packages as suggested in Can't boot after following tutorial for interrupted update, I rebooted now it works as it should!
Thanks a huge lot for all your help!
Sehr schön!
Wonderful!
All the best!