Nostr: How do I move from one Nostr client to another?

Short answer

Open the new client using a trusted signing method for the same keypair, then check its relay settings and whether it can load your profile, follows, and posts. Your identity is not bound to the old client, but data availability depends on relays and feature support. Export or note important settings before leaving, and never send your private key to the old app as a transfer step.

Sources

NIP-01: Basic protocol, NIP-02: Follow lists, NIP-65: Relay lists.