This is a source code only project, containing a portion of the overall function needed to provide a full Java Developer's Kit (JDK) implementation. To run Java applications, OpenJ9 must be combined with the non-VM parts of a JDK, such as OpenJDK.
The project uses GitHub issues at the main repository (eclipse/openj9) to handle the work of the project and communicate with the community. There is a slack workspace for all users, adopters, and contributors/committers to be able to reach out to the community, and a Slack link on the OpenJ9 main web page enables anyone to join. The dev list is used sporadically, and is monitored and questions answered. There is a weekly community web conference, where every so often short talks about features are presented. For details see the #planning channel on Slack. It's used to discuss interesting issues for the project, external participation is welcomed. The meetings are recorded and made publicly available on YouTube. There are a number of articles, some listed here https://www.eclipse.org/openj9/oj9_resources.html. Several committers have delivered talks at conferences like Java One, QCON SF, CASCON, FOSDEM, and there are talks scheduled at future conferences to continue to get the word out.