Meshtastic is an open-source, off-grid mesh networking project that lets you send messages and view node locations over long distances without cellular service or the internet, using inexpensive LoRa radio hardware.
Features include:
Connect to your Meshtastic device over Bluetooth, USB serial, or Wi-Fi.
Messaging: swipe to reply, double-tap reactions, per-contact drafts, pinned and unread conversations, bubbles, proven delivery receipts. A Units setting. One search bar for nodes, messages, settings and docs. Settings take labels, units and firmware gates from the schema. Map layer opacity and role filters. Lightning, particulate and soil telemetry. Tap phones to share a contact or channel. KML import works again.