You can get a high-level overview of the standalone on the Wiki. The chief difficulty is creating something that a user can double-click on which will install and configure a suitable database. Previously, MySQL provided a JDBC driver called MXJ that would automatically start an embedded MySQL instance from a JDBC connection URL, which was key to making the standalone work. However, that product has been discontinued (so no longer receiving updates) and there were never binary versions for ARM-based processors (it was discontinued a long time ago, before ARM-based machines were popular). Basically, this project needs to either come up with a way of replacing that (there are a few options), rework OpenMRS to be able to run on an embedded Java-based database (we already use H2 for integration tests, so it’s probably easy).