The other app I use is Briar for communications. It's surprisingly handy. You can use it on existing wifi networks but also mesh your own network with Bluetooth.
Joplin to journal my vacation (which then synchs to my home network).
Oh, and of course Wireguard!
Thinking I should add a "pre-download" feature where users can generate audio guides and itineraries over WiFi before heading out. Would that solve the offline problem, or do people need the flexibility to explore spontaneously without planning ahead?
But you're right - Google Maps handles destinations well, but there's no reason we couldn't use Gemini with grounding for transit guidance too. That's a really interesting idea, thanks! Definitely going to explore that.