jon_slider That’s the thing, I’m not judging by a single factor like weight, although I highly prioritize it. I also don’t want single-use batteries. Plus the lack of a reflector or lens I think makes it less versatile. Totally agree that finicky lights are not worth it.
I think the best products are well-optimized in relevant features to maximize usefulness for a given purpose, rather than maximized in one or two specs.
chinooker Oh that’s a very nice knife size! The image made it look bigger.
riffraff A neck lanyard isn’t for me. But that’s a nice collection you’ve got.
MascaratumB Yes, the RovyVon A series are quite appealing… except for price! I just can’t stomach paying more for a keychain light than the SP33.
pc_light I appreciate the pic of all of them together! I have yet to test out the C01S, but I’m not sure if the differences between those AAA lights would be noticeable in practice.
Rat_Racer Yes, the Olight i1R is one of the best contenders. Sealed battery is maybe the biggest downside.
azj Thanks, but I’m not keen on non-rechargeable, button cells. That thing is next-level tiny, though! I like how they describe it as “tactical” haha
Boaz Quite right, but the charger is going to be a computer, which I’m virtually always in front of, so the keys will still be with me. 
This would be a bigger argument against a keychain USB drive since a file transfer can’t be interrupted, while charging a battery can. Despite this, my keychain USB drive has also proved itself useful to me. Also, in contrast to your use case, I sometimes go without cash or wallet, but not without keys. Different strokes for different folks! 
shirnask Great sale price! Unfortunately shipping kills it for me at 66% of the flashlight cost.
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Now for some news!
I’ve come to terms with the very real possibility that what I’m looking for may not exist. So I reached out to Sofirn to see if they would be interested in making something meeting my requirements.
It turns out they have plans to make a tiny EDC keychain light! Check out this thread with a group buy interest poll and to discuss the design: [Group Buy Interest Poll] Tiny EDC keychain light done right - BLF/Sofirn-style!