The Microsoft interactions are driven by an OpenXR extension that's specific to MSFT, so we don't support it and don't currently have any plans to.
Unity's XR Interaction Toolkit doesn't currently support hands, but it's on their roadmap as "under consideration". You can vote on this issue to make Unity aware of how important it is here.
To build interactions around hands with OpenXR the easiest way currently is to use the OpenXRProvider and connect that up to MRTK or the Interaction Engine.
We have tested the provider with v0.1.4 of the plugin and were able to get this working so we suspect there is something else going on here to cause this issue. Please can you send me a screenshot of the exact errors that you are seeing to firstname.lastname@example.org so I can investigate further?
Please note that the branch on GitHub does not contain the OpenXR plugin package. You will need to add this yourself to get this to work. There are instructions in the readme, but it does mean that when you open the project you will get errors.