I believe it's due to the mirrorless system.
If the 20 1.8 is a G lens, then I don't think C1 or LR will load a profile automatically. Nikon like Fuji and most other mirrorless cameras, embed the lens info and it can't be changed. But like you point out this is only going to be for a mirrorless Z lens. I believe that it's going to have to be a manual add like you have found. But not sure if anything change can be done since all focus by wire mirrorless lenses seem to all have the lens info automatically sent to the raw file and that is what is loaded when the file is opened in C1 or LR.
LR would have no lens info loaded either for this solution as there would be no Z lens info carried forward to the exif.
I have yet to find a mirrorless solution that doesn't work this way, from Sony, Fuji and now Nikon.
Paul C