[seL4] L4 Risc-v touchscreen board

I am newby in this sector and involved in a project to create a prototype (hardware and software) based on risc-v cpu and running L4-based microkernel. I need to control and program an attached touchscreen where I can create a simple graphic user interface too. I would appreciate any suggestion that bring me on the right road. Board should embed wi-fi network too. First step is to find the right hardware and second is to have development tools/environment to program the board. As much as possible open licensing should be adopted because the project falls in IT security solution and want to avoid any hidden backdoors. Thank you in advance. Best regards, Luca