Is it possible to add an HDR to the default 9 that blender comes with

Question

I want to add it into the default library (drop down window headed Viewport Shading),NOT just create one using an environment texture node within the Shading setup.

Answer 1

You can find the respective menu in the settings under Lights. Any HDRI can be used here, but i'd recommend scaling it down for its use as a preview first