HololensXreaUnity: A C# repository from sosunnyproject

Configuration for archive note: Build Hololens 2.0 with Unity MR Toolkit

Unlike Unity AR, which sets up each scene in different Unity Scene files, Hololens MR requires you to put all assets in one scene. So it doesn't need to keep changing the scene depends on the marker image. Or that's how we did it to prevent bugs/overloads.
The angles of where the model pops up (compares to the angle of marker image location) works almost same to AR version
Shader URP and lighting and sound work okay. Touch & emit the particles interaction is not working great on MR.
MixedRealityToolkit configuration: you can clone and create a new profile, name it as 'MyMixedRealityRegisteredServiceProvidersProfile' and use that in config setting.
(I think...) You don't need Vuforia engine unless you want to recognize the 3d object in real life and augment sth in your MR hololens.

Here, we used 'Manager Scene' in 'Scene system' of MRTK.
Then, added the actual MR playing scene in Scene Loader game object with LoadContentScene code.
XreaManage Scene contains MixedRealityPlayspace which is an empty object but has main camera as an only child, MixedRealityToolkit which includes configuration, SceneLoader which loads our main player scene (XreaImageTarget that has all assets for augmentation)
The screenshot below is the scene configuration of sample scene that mentor built it as a test for interaction.
It's a bit different from our MR main scene. This example below has its own main camera where as our main MR Play scene gets loaded by Manager component.

The image size has to be in exact unit. Otherwise, it might cause the augmented models position/angle bit off.
I had to change 100 to 75 for accurate recognition.