Hello again v1X3Q0!
I’m sure you are already aware that if you get the pointer and manipulate it directly you will lose support for anything but certain windows platforms, but I feel awkward not mentioning it, so sorry about that 
Anyways! Searching a bit in the solution, it seems very possible to access the device directly, even without Cpp haxx.
One thing I found was a global in DynamicRHI.h:51 (GDynamicRHI).
You will of course have to include the RHI module in your build scripts and include the proper header file in the place you want to access it, but you can then cast and get the device like this:
Your build script:
PublicDependencyModuleNames.AddRange(new string] {
//Other stuff
, "RHI"
});
Your code:
FD3D11DynamicRHI* D3D11RHIPtr = Cast<FD3D11DynamicRHI>(GDynamicRHI);
ID3D11Device* DevicePtr = D3D11RHIPtr->GetDevice();
I’m pretty sure you will need to schedule any operations you want to do with the device on the render thread to avoid problems, but you can check out my plugin for how to do that.
And you would also of course need to include the D3D11.h header for the interface. 
I didn’t actually try this, so there might be some other stuff you need to do, but it seems like it would work 
I would still strongly recommend converting your code to the general RHI format though. Not only because doing direct access like this is fragile, but also because it might mess with the renderer and give unexpected results or slowdowns. If this is just for a test, I guess it doesn’t matter, but I really strongly suggest your just port your code
Best regards,
Temaran