Here’s a wearable + subscription idea!
Socks that are sent to you monthly in a subscription package similarly to Dollar Shave Club.
Once you sign up, you also get a machine which takes care of the pairing chore of these socks. All you need to do, is to dump them after washing.
Each sock comes with a UUID embedded and visible only to UV lights. The machine can read that, and pair them automatically.
Not so hard to build, and given DSV’s billion dollar exit to Unilever in 2016, the opportunity/challenge is exciting.