VR on smartphones is all but dead following the end of Samsung's Galaxy VR ambitions and Google's recent announcement that it has ceased development for its Daydream VR platform. However, in an inkling of hope for those who were sold on the idea, Google has open-sourced its Google Cardboard VR headset design so that it might have a second life.
https://www.notebookcheck.net/Google-Cardboard-open-sourced-as-a-lifeline-for-mobile-VR.441427.0.html