From what I can understand Nvidia seems perfectly capable of running DXR 1.1.
Nvidia seem to suggest they themselves support it.
They do, i said that, just as RDNA2 supports DXR 1.0, just not natively given the way AMD are Nvidia run their Shader and RT instructions Asynchronously is entirely different at the architecture level. Read the article i linked, its a quick rundown in the backend code differences.