The boot flow diagram on the article indicates the user gets dropped off into EL1 and not EL2, sadly though. The article is from Qualcomm so I would assume this the current official situation.
Arm SystemReady SR/ES assumes sane ACPI tables. That's something that Snapdragon X (1st-gen) very much doesn't have. The ACPI tables present there are pretty much only usable for Windows if you want full functionality.
Yeah ESXi-Arm is bootable, but a number of patches were required.
The system firmware will ship with 3 boot modes selectable via the setup interface:
- Windows (this one has the Windows tcblauncher escalated to EL2 through Secure Launch)
- Linux (this one stays at EL1)
- Linux w/ KVM (which jumps to EL2 before kernel handover)