Hi Patrick,
I am not sure if anyone is using HBase specifically as their data store. IMO essentially what you can leverage is the client SDK which Hbase provides which is available for languages like java, scala etc and integrate the same with AEM.
You can write a custom submit action which would make a connection to HBase the write the payload there. If you want to make the solution more generic, you can create a bundle for CRUD operations for a given Hbase table. The submit action invokes some service from this bundle and performs the action of ingesting data.
Please have a look at https://hbase.apache.org/apidocs/org/apache/hadoop/hbase/client/package-summary.html or google Hbase client java to get some examples.