My wishlist (top-down from pragmatic to fantasy):
- fully compatible with official firmware
- BOOTSEL via i2c registers
- stm32 power draw reduction and standby mode (pico wfi, stm32 wfi, wakeup by keyboard/rtc)
- programmable backlight via i2c registers
- persistent backlight level driven by pico
- expose internal RTC via i2c registers
- remote gpio/uart via i2c registers
- run BASIC/MicroPython/etc. programs via i2c registers
- two-way communication via i2c registers