The unit IS in fact UEFI (which is what CSM support is all about - to allow a UEFI device offer legacy options to older operating systems and/or hardware devices.)
Here's what I see:
1. You have legacy (CSM) enabled - this is likely a requirement for Windows, but you may need to disable it for sys/extlinux and possibly grub
2. You have boot0 and boot1 which are VERY likely boot partitions from the original Windows installation - this we may have a slight problem with
3. For unknown reasons, you have your USB device (sda) double-partitioned (sda1 = Partition 1... which is then re-partitioned as sda1p1)
@jazzbiker: The eMMC isn't configured like a RasPi so piCore references aren't really helpful here. LOL, plus it's an Intel, not an ARM processor.
With RasPi, the system doesn't usually come preconfigured with multiple hardware partitions. With EC-9100, it does - which requires a compiled boot-loader.
The closest guess I'd be able to offer is that we'll need to install GRUB onto boot# and have IT point to mmcblk0p1. "Logic" tells me this should have been boot0, but it's looking like boot0 may not have "space" to put a boot-loader in. Let's find out, shall we?
@newbieCore: Please boot the laptop and at the shell type in fdisk /dev/mmcblk0boot0 [ENTER]; once in, press "P" to get a layout. Specifically, we want to see what it's SIZE is. (Screen shot likely helpful!!) Press "Q" to exit, then repeat the process for /dev/mmcblk0boot1 - again, a screen shot may be useful here, too, of the "P" screen.
If boot0 has "size" and enough to cram GRUB into it, that's our goal. If it doesn't, I cannot fathom why it exists in the first place. For Windows, it needs a boot partition of a few MB to install a boot loader and a menu - normally this is a single partition.
Once we have that information, reboot the laptop and go into settings -- this time, turn off CSM -- reboot again and go back into settings; you may now have new boot options. If so, please send along a screen-shot of this, too.