A day after the Pixel 4 launch, Google confirmed it's backing down from its Daydream VR project. And while Google's mobile VR ambitions are on hold for the foreseeable future the company announced its opening its Cardboard SDK to developers with hopes of prolonging its life span. According to the official statement on Google's Developers blog, the company claims it managed to ship 15 million Cardboard headsets worldwide but usage of the low-cost VR headset declined significantly over time. This is one of the reasons why Google decided to stop actively developing the Google VR SDK....
Source: https://www.gsmarena.com/google_releases_cardboard_open_source_code_in_bid_to_keep_its_mobile_vr_alive-news-39993.php