MarsMap shows you an observing ephemeris of Mars: the major features visible on Mars at any given time.
On a computer, you can drag the sphere around using Shift + mouse drag. There's currently no alternative on a phone or touchscreen.
You should be able to install MarsMap as an app on the home screen of Android or iOS phones and tablets: look for "Add to Home Screen" in the Chrome or Safari menu. It doesn't collect personal data or need any special permissions, and shouldn't need to use the network at all once you have the app downloaded.
Written by Akkana Peck, originally in C for Linux and PalmOS devices, subsequently translated to Java and then JavaScript. Marsmap Source code on GitHub..