IP68? The 6 stands for absolutely dustproof and the 8 means it can be submerged more than one meter in water and still work. Wasn't there a case of a working iPhone from a lake?
Disclaimer: prefer changeable batteries and don't own Apple devices.
iPhones are not waterproof. Warranty do not extend to water damage and iPhones have internal indicators of water leakage. If Apple is not confident with iPhones waterproof properties, neither should users.
You're right that water damage isn't covered but they're still pretty resistant:
> iPhone 12, iPhone 12 mini, iPhone 12 Pro, and iPhone 12 Pro Max have a rating of IP68 under IEC standard 60529 (maximum depth of 6 meters up to 30 minutes).
Disclaimer: prefer changeable batteries and don't own Apple devices.