jeez! i thought i'd received a dead pico2w (didn't test it before installing the shim, mea culpa) but no! you need to press the power button on the shim even without a battery and plugged into usb, then the pico works as intended!
i now have Stefan's basic running on the gizmo with full graphic capabilities of the monochrome 128x64 display and implemented a FatFSUSB driver so i can save files and transfer them to a computer
it's not perfect, some keys are not quite aligned and so are harder to press than they should be, but it's leagues ahead of trying to use it as a collection of loose parts on the bench
@mavica_again Actual handheld testing