As promised, Skylum released yesterday the HDR extension to Luminar Neo. Before activating the extension, it was first necessary to install the latest update to the app, numbered 1.2.0. Once the update had been installed I went to my Luminar member account from which I was able to activate the extension with only a single click. Upon returning to the program, and while still in Catalog mode, a panel then appeared into which photos could be dragged for HDR editing.
Along with the extension I was able to download two sets of HDR presets I had preordered along with a set of dramatic HDR skies. Interestingly, though when preordering I had been instructed that the presets would work only with Neo, I also received two additional sets of the same presets in the form of Luminar AI templates. I'm not sure how well these latter will work, however, since it is only Neo that has the HDR extension. I will have to experiment and report back later.