Comment by yencabulator

You can get pretty darn tiny USB sticks, if you let go of the metal keychain requirement GP had (some of these work with a thin lanyard, think pocket camera strap).

https://www.amazon.com/SanDisk-Ultra-128GB-Flash-Drive/dp/B0...

USB-C too, though they stick out much more because of the tinier connector: https://www.amazon.com/128GB-PNY-Elite-X-Type-C-Flash/dp/B0D...