Ortlieb Snack/ Mask Bag A6
These little bags are great. They're made in Germany of sturdy food grade PVC-free plastic. It's a self-sealing rolltop design with velcro for extra security. Comes with an optional lanyard.
They're a size A6 which is exactly the size of a passport.
We've mainly been selling them for use as a mask bag, but they were originally designed for trail mix, etc when you're hiking. (Or if you have toddlers and always go out armed with multiple granola bars, they're great for that too).
Waterproof so they'd also function well as a drybag for a smartphone.
Discontinued, while supplies last!