Well, it seems that even the smallest variant, that is Google Pixel 4, has a gray version, as evidenced by the following photos, published on Twitter by Max Weinbach:
Google Pixel 4 in gray, a missed opportunity?
According to what can be learned from these photos, this variant seems less prone to fingerprints than those that the Mountain View giant decided to choose for marketing
According to Weinbach, the Google Pixel 4 protagonist of these photos was made before the diffusion of the images leaked iPhone 11, excluding that Google may have been inspired by them and specifying that it was produced with the intention of being marketed (but then it was put aside to favor other colors).
Unfortunately, we will hardly find out what the name chosen by the Mountain View giant would have been for this color variant, unless (hypothesis that, at least at present, it seems rather remote) should not change its mind and decide to launch it in the coming weeks.