Rasplex kiosk overly for install on top PMS raspberry pi 3B



I am trying to make a self contained media server, while i am running the PMS for raspberry pi, the localhost UI from the web browser is meant for a larger screen, not the Official 7" raspberry pi touch screen. What i want to is use the rasplex UI and the interface for it. I know that you can't do Libreelec and Rasbian on the same device. ( I have a new model in the works that separates the two) But can some one direct me to the repo where all the UI data is stored? thanks