Ubuntu was never offered on the Aurora R7. That being said, most versions of Ubuntu are Microsoft-blessed, so you shouldn’t have any SecureBoot problems. Try removing the PCIe/NVMe SSD, and try clean installing to a blank SATA drive instead.
When booting in efi mode you have to tell the kernel what the name of your initrd is.
So on the img args line, add initrd=initrd-ori
This is documented in several places, but is specific to what the Linux kernel needs to know which file in efifs that it should load, if any.
Old EFI enabled machines have CSM (Compatibility Support Module) which when enabled allows for EFI firmware to enter bios INT 13 mode. This is not allowed on new Class 3 UEFI machines which are 64 bit Windows 10 only.
Your only option is to install Ubuntu ALONGSIDE windows after windows has been loaded onto a separate EXTFS partition.
In Legacy pcbios mode there is INT 13 which is used for disk access, this does not work for current models that are Windows 10 64 bit only.
UEFI the partitioning is a bit different. They use GPT instead of MBR partitioning now, and the UEFI reads something called an EFI system partition (ESP) that needs to be in FAT32. There you put grub2 and the windows boot manager and boot loader.