Generally it can be difficult to get Linux on Bay Trail or Cherry Trail devices, but that's mostly due to the lack of support from the device manufacturer, not on anything related to the Intel SoC. The ease of installing Linux on the GPD WIN will be determined by GPD themselves. It may be in a state where it can boot linux, but some peripherals like the keyboard, analogs, sound, bluetooth won't work because proper kernel modules need to be made or device tree setup etc.
EDIT: In time even without GPD's support it may eventually get proper Linux support, but out of the gate I doubt it unless GPD initiates it themselves.