Yondo

Plans you a walkable day in any city, then works with no signal at all. iPhone only for now — two steps and about a minute.

Install TestFlight

Yondo isn't on the App Store yet, so it comes through TestFlight — Apple's free app for trying apps before they're released.

Once TestFlight has installed, come back and tap this, then Accept and Install.

Two things to know before you start.

It lands on your home screen as Yondo Beta. TestFlight lets you know when there's a new version.
Upgrading in the beta is free and charges nothing, so try it. Everything else is real.
To send feedback from anywhere in the app, take a screenshot and tap Share Beta Feedback.

Anything at all is useful, but these are the things that are hard to find out without someone actually travelling:

Places it missed. Somewhere obvious in a city that it didn't suggest — that's the most valuable thing you can report.
Opening hours that were wrong. There's a report button in the app; using it sends the correction straight back.
Whether the day was actually walkable. Too rushed, too empty, too much walking between stops?
What happened with no signal, once you'd downloaded a city.
Anything confusing, especially in the first two minutes.