The gripper from madvapes takes a single 123a. The precise 16340 from super-t is another one. Let's see... mini copper, xs-haler, and the spark plug also come to mind, but I'm not sure if any of those are currently available. There might be others that take singles.
It bears mentioning that lots of tube mods can take pairs of 16340s... but it's going to be tough to get anyone to recommend using stacked 16340s in anything but a Buzz Pro now. There have been recent injury accidents reportedly (or at least assumed to be) involving stacked 16340s in unprotected tube mods. Your Buzz Pro has the best protection available, but all-mechanical tubes have nothing but maybe some vent holes. I'm certain there are other people besides myself who have confidence in the quality of battery they have and in the venting provided in the mechanical mods they stack batts in... but it has become a hot-button topic on ECF and there is almost zero likelihood you'll find anyone willing to recommend doing it.
EDIT: Two more mods that I should have remembered -- The Megalodon in mini mode will take either an 18350 or a 123a single. And, the regular sized Rough Stack (not the maxi rough stack) will also take a single 18350 or single 16340.