Recent efforts in stereo viewing focused on AR/VR headsets, because these devices made most 3D displays obsolete. Headsets are more portable, cheaper (Meta Quest headset is $300-500), provide larger field of view (full immersion), and offer full 6-degree-of-freedom viewing and interaction. When you need to see the surrounding real world then you can use an AR headset, such as the HoloLens. Both AR and VR headsets are usable in Slicer view the SlicerVirtualReality extension.
For headset-free viewing you can use holographic displays, such as the LookingGlass, which is already supported by Slicer. Holographic displays have the advantage that they can be viewed by many viewers (no head tracking is needed).
Single-user 3D displays don’t really have much place anymore other than maybe they can try to compete in price or image resolution. I think such monitors (such as the zSpace) are already usable with Slicer (maybe via SlicerVirtualReality extension?). If SpatialLabs provide OpenXR interface then you can probably use SlicerVirtualReality extension. Otherwise you can ask the manufacturer to contact Kitware about how they could add VTK support to their monitor.