I’ve recently completed successful testing of a prototype that enables sending Bitcoin transactions between mobile phones — with no Internet connection, no Wi-Fi, no cellular data, no Bluetooth.
By any chance, do you use screen (that show QR code) and camera (which scan QC core) ?
Key features:
✔ Fully compatible with Bitcoin transaction structure (validated on testnet)
✔ Secure: no replay/double-spend vulnerability
For these points, IMO it's not worth to mention since your usual offline TX does same thing.