Kingston stopped making the one I really liked. A truly small microSD to USB adapter that could fit in a wallet. This was perfect for always having a USB drive around and not taking up space in your pocket.
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://external-content.duckduckgo.com/iu/?u=https%3A%2F%2F...
https://www.bhphotovideo.com/c/product/658398-REG/Kingston_F...