The Unity plugin now lets you connect to a session of Houdini Engine running inside Houdini. The state of Houdini Engine can be viewed in Houdini while working with the plugin in Unity. Changes you make on either end, whether in Unity via the plugin or in Houdini via its various interfaces, will be synchronized to allow both applications to make changes and see the same results.
This feature was under development for a future release but was backported into Houdini 18.0.499. Learn more – https://www.sidefx.com/community/houdini-18-backport/