That is great news, and very encouraging! Of course the bootloader / boot process has to be able to be modified as well; we'll see how good/bad Dell does with that.
Here's what they say about the boot process in the blog post:
> The boot stack on Snapdragon X Elite supports standard UEFI-based boot. Linux boots up using devicetrees, and all standard bootloaders, including Grub and system-d boot, should just work out of the box. We use Grub to boot into Debian, and to dual-boot Windows and Debian.
> We’re working closely with upstream communities on an open problem with the UEFI-based BIOS while booting with devicetrees. The problem is that, when you have more than one devicetree blob (DTB) packed into the firmware package flashed on the device, there is no standard way of selecting a devicetree to pass on to the kernel. OEMs commonly put multiple DTBs into the firmware package so it will support devices with slightly different SKUs, so we’re keen to solve this problem. (See the Embedded Open Source Summit presentation on this topic by my colleague Elliot Berman. Links below.)
Only time will tell how good the support is, but it's at least a start.