To put my issue into perspective. I installed fresh install of LEAP 15.3 EFI with secure boot enabled. The installation went fine.
Then I booted into rescue and made those following tar archives: boot.tgz (boot/), boot-efi.tgz (boot/efi/), home.tgz (home/), root.tgz (/). Then I wanted to test my installation from scratch via USB.
So I formatted the drive, created efi partition with a size of 1GB. Then created a second partition, this time LVM. Then I created appropriate LVMs.
I have untarred those tar archives into appropriate places. After that I called mkinitrd and then proceeded with:
grub2-install --target=x86_64-efi --efi-directory=/boot/efi --removable --boot-directory=/boot/efi/EFI --bootloader-id=grub /dev/sda
Installation went fine but the problem is I cannot boot into the opensuse-secureboot system for some reason I am missing. When I choose that option, it justs refreshes right back or it goes black screen for like 1 second and then I am back in boot menu. Could it be somehow related to certain keys or certificated due to secure boot ?
Also, this method works fine for non EFI installations. But EFI is a different kind of issue.
Any ideas ?