Things may change soon (no pictures available so far):
If you want/need the complete Roon experience, you have to use the Roon client software in some way. There are ways to configure tablets/phones in kiosk-mode as dedicated Roon control (others, who use their tablets/phones in such ways, might provide information how to setup if needed). You can also use a AiO, laptop or PC + Touch Screen combination with auto login.