Nostr super power is relaying between devices. I've been thinking on places where the data just needs to transit, not persist -

Yesterday was thinking about copy-paste/clipboard apps. Copy on one device and paste on another. There are open source multiplatform clipboard apps which could enhanced in this way. 

 I also love the Obsidian Nostr plugin, but would further enhance it to make it bi-directional and sync between network and local stores.