Turns out that having a display pin shorted to ground makes for a very non-working display. The repeating pattern is to fit the 128x128 test image in a block RAM before hooking it up to a real framebuffer interface.
@polychrome the plan is to build a new main board that fits the pi and adapts the display, keyboard, touch screen and battery holder. I'm reusing most of the design from my Pi + Model 100, although the ice40up5k doesn't have enough pins by itself.
@th that is amazing.