My girlfriend's grampa alternates between two computers and he sometimes travels. He wants his will, a few other other important documents, and maybe a few hundred photos always available, but does not want any cloud solution of any kind. He's not very technical and becomes overwhelmed sometimes, so we need a compromise between reasonable security vs. a process he can work with and remember.
A scenario he's comfortable with is a flash drive on his keychain (with an offsite backup he can update as needed). Important features are ruggedness and reliability, as he's very active for his age. We don't need high capacity, and encryption would be outside the bubble of manageability for him. His security will have to be all physical; he guards his keychain like a hawk and never loses it (nor forgets it), so that seems like a reasonable place to focus.
I'd like to be able to recommend a good drive designed for keychain use, ideally with a metal casing that resists denting and keeps out dirt and dust (a presence in one of the environments he travels to). But I also want high reliability, not something from aliexpress that looks great but will conk out in a few months. In the past I've seen some that come in an aluminum cylinder with an end that unscrews, and that would be fine since he will only access it occasionally (having to spend a minute or so to physically prepare the drive is not a problem). I really don't want one of those gimmicky ones where a supposed "cap" swivels around on a pivot point. I've used those and found them annoying because they swivel around in the pocket.
So I'm looking for recommendations from this community for (a) a physical configuration that would be convenient yet rugged to live in the pocket of his jeans for the rest of his life, and (b) brands that you've found to have high reliability.