I asked nostr:npub1ey6qdmvzcgcsr883m9nspzz0mm037l26xtardzcskfsvc6gc7jssm9szvp about this and he said that nostr:npub1jugar2agq6369p0l86razavs9shj2p6pscxecevs8j94ap37hkqsjlfc28 SDK also doesn’t expose the Spark public key. So there doesn’t seem to be any reason for it.