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No, this is a terrible idea.
Nostr describes a way to transmit data, not store it. Storing data in this way doesn't actually save you anything:
  • You're still setting up a server
  • Your client still needs to call the data
  • You're adding in extra query overhead because it's not really structured
    • It'll be much slower and less scalable than using a proper database
Focus on what nostr is good at, hole-punching and distributed-ness.
Don't get distracted by what it isn't good at.
A better way would be just to use better structured json or sqlite with generic storage adapters so users can save anywhere like their cloud drive or ftp server of preference.