Marble

KDE Marble is a virtual globe and world atlas (comparable to Google Earth). As an education tool it can view many different world maps (e.g. historical ones) and even astronomical / planetary maps.

Installation
Marble is shipped with Alpine, thus it can be easily installed in pmOS:

Mobile version
Per default, Marble launches in desktop mode which is barely usable on mobile (even with tweaks like Phosh). But you may use the command-line option  to launch a mobile-friendly interface. If you want to link to the mobile version from your homescreen, place a -file in   with following contents: Be aware that buttons in the map view are not usable via touch input, instead gestures are supported (pinch to zoom, swipe to move).

Using Marble
Any higher-resolution maps need to be downloaded and opened. Access the respective dialog via. Using the newly opened window with touch is not really intuitive, you need to drag the scrollbars to scroll. Choose your map(s) (e.g. OpenTopoMap, Public Transport, Hike and Bike Map etc.) and hit on the right side. When downloaded you can open them via.

In portrait mode there are some overlay problems (Download dialog and footer): Multiple letters are overlapping which makes both underying phrases unreadable.