Tank007 E09 is about 1.5x longer than a AAA and slimmer than a AA.
Had one on my keyring for years and only just switched it out for something different. Bargain 3 mode twisty if they are still available.
I have an oLight that serves the one-mode thing, but thank you for the suggestion. … 
I have accumulated five AAA lights over the years from a Fenix LD01 and a E05 in stainless to a Titanium Innovations Illumina TI and a couple of ITP examples, one stainless and one black aluminum. I keep Energizer Ultimate Lithium batteries in them as I have never had a leak, they deliver high current and have excellent shelf life. As for length differences in them, the differences in size are so minor that it makes no noticeable carrying difference in my opinion. They are pretty generically small with the shortest at 68.5mm and the longest at 75.4mm, a difference of about 7mm or about 10%.
If you want short though combined with light output then it is hard to beat the RovyVon Aurora A series key chain lights. My older example, stainless and with USB Micro charging, is under 54 mm long and is 14.4mm in diameter. The diameter is slightly larger than 4 out of 5 of my AAA lights but by less than a millimeter. Mine is marked as a A2 and was bought in early 2018. Still looks new and holds a charge. Also puts out far more light than any of my AAA lights. The big disadvantage is the non replaceable battery but if you want an unobtrusive keychain light then this, and it’s current USB C charging cousins are it in my opinion.
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If you want absolute minimum size with a replaceable battery take a look at the MecArmy keychain lights. they use a replaceable 10180 battery and my example is 46.8mm long and 14.6mm in diameter in stainless steel. Single mode at a claimed 130 Lumens and it has a USB Micro port for recharging it. Wish they offered a moonlight mode too. Basically the same size as some of the mini lights from 10 years ago which took multiple small watch batteries such as the 357 size.
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