For example, on the Raspberry Pi, you'll need the kiosk user to be part of the video and input groups. You may also need to update the permissions and group ownership on /dev/vchiq if running on Nerves since it doesn't yet do that by default.
about this description, how can I set permissions for /dev/vchiq
https://github.com/nerves-web-kiosk/webengine_kiosk#permissions
about this description, how can I set permissions for
/dev/vchiq