SLI and the like have pretty much gone the way of the dodo for gaming…. The last SLI setup I had was 2x 980Ti and even back then support in actual games rather than benchmarking or demos was really dying.
A very small handful of actual games supported VR SLI (most croteam titles mainly iirc) but since then to my knowledge Nvidia hasn’t done any further development and have even removed the actual ability to even use SLI on their ampere line (all except for the 3090). You’ll note for example that the Nvidia VRworks VR SLI API only supports DX11 (plus OpenGL and Vulcan), and given the engine is moving to DX12 shortly it likely isn’t even usable without substantial work. Given Nvidia have all but dropped SLI support on their own product line it is highly unlikely they continue to develop it either.
Also note it is only compatible with maxwell and later, which deletes the vast majority of your list of supposedly compatible GPUs… they are SLI compatible but not VR SLI compatible. Not that they would be relevant anyway as they can’t run DX12 and MSFS DX11 support will be switched off in the not so distant future.
The next step on the GPU front instead will be larger MCM GPUs which are essentially invisible to the game engine and instead addressed as a single larger GPU… allegedly should see that arriving with the next generation of Navi from AMD, and probably not until Hopper for Nvidia which will be a generation later.
Spending time trying to support VR SLI would be time and resources spent on what was always a very niche (and now even more so) hardware setup which has a very limited present and no future. Even when it was “current” developer support was abysmal, now that it’s largely consigned to the history books for gaming I don’t see that situation improving… instead the industry is headed towards MCM and more efficient APIs, alongside ML based up sampling techniques on the GPU front, and for VR likely combining it with dynamic foveated rendering along with eye tracking on the HMD side for potentially large performance wins.
Their time, in my opinion, would be much better spent adding support for advanced DX12U features that have the potential to greatly assist VR performance (as well as flat screen!) for a much greater proportion of the user base such as sampler feedback, variable rate shading, mesh shaders, ML based up sampling etc and will continue to be relevant for years across both current and future generations of hardware.