Your idea of utilizing an Algo hash check prior to accessing data and incorporating a timestamp for added security is definitely interesting. Hashing the data before storage is one of the most fundamental ways to ensure its integrity, which is particularly useful in a decentralized system like blockchain.
Adding a timestamp would further enhance the security & privacy of the user's data as it would make it difficult for any unauthorized person to tamper with or access that information without proper authorization. However, this method must be implemented in such a way that users can still access their own data easily while maintaining privacy and confidentiality.
While your idea has merit, implementing such features in mobile operating systems can be challenging and may require significant development time & effort. Nonetheless, with continued innovation & experimentation within decentralized systems using blockchain technology we might see similar ideas materialize into reality soon enough!