$ lsblk -o name,label,size,fstype,model

sda 149.1G ST3160815AS
├─sda1 EFI 260M vfat
├─sda2 debian 146.9G btrfs
└─sda3 2G swap

$ efibootmgr -v

BootCurrent: 0000
BootOrder: 0004,0000,0001,0002

Boot0000* debian HD(1,GPT,02cdc5ec-79c3-411b-a1ed-2614cdb6d9e5,0x800,0x82000)/File(\EFI\debian\shimx64.efi)
Boot0004* Debian HD(1,GPT,4904e13d-5206-480f-9fc8-7cf0895845be,0x800,0x5f000)/File(\EFI\DEBIAN\SHIMX64.EFI)

＜＜　File(\EFI\debian\shimx64.efi)　のじっさいの所在を確認

# ls -R /boot/efi
/boot/efi:
EFI

/boot/efi/EFI:
Debian10 debian

/boot/efi/EFI/Debian10:
BOOTX64.CSV fbx64.efi grub.cfg grubx64.efi mmx64.efi shimx64.efi

/boot/efi/EFI/debian:
BOOTX64.CSV fbx64.efi grub.cfg grubx64.efi mmx64.efi shimx64.efi
#