Correct that a Pi cannot attach to a Duet 2 via ribbon cable high speed interface until the Duet2 firmware is updated.
However... There are two ways to use a Pi as a touch screen interface to a D2 that work right now.
Run the DWC interface in a browser on the Pi. The D2 and the Pi must be on the same network. This can be any mix of wired and wireless, as long as their IP addresses can reach each other.
It is literally as simple as building a vanilla Pi, with touchscreen, and launching a browser and entering the Name (or IP) of the printer.
Connect the one of the Pi's UARTS to the same port on the Duet 2 that a PanelDue connects. This is just TTL serial, so PI TX <> Duet RX and vice versa.
Then, write your own touch gui. Have it issue the same commands a Panel would... and display the status of the printer by "polling" for updates, just like a Panel does.
Easy to look at github and see all the commands. Being a Pi, that gui could be Python, NodeJS, or any of a dozen other languages.
Obviously path 2 is more work; it also allows TOTAL custom GUI. BIG BIG buttons for start/stop/home, whatever. Scrolling screen for other buttons. Whatever your heart desires.
