You can use that app on location to see a visual image of where sun, moon, and Milky Way will be at certain times.
I use the 2D features of PhotoPills in conjunction with the 3D features of TPE and really enjoy that combination.
I won’t spend a lot of time covering these applications, but you should definitely play around with Google Earth and Google Maps if you are looking to scout a new location. Google Earth provides 3D imagery for the entire planet. The resolution is amazing and you can a good idea of how an area looks just from using the application. I use it every single day to see what locations look like and to try and find new spots. It is incredibly powerful. I also use Google Maps a lot, mainly for their street view options. I can get street view images from many locations around the world. There is also public panorama imagery integrated with street view, and many times I will find those points on Google Maps for trails or other less visited areas. I use the 360-degree panoramic images to get an idea of how the area looks. Nothing beats being there in person, but these are great applications to help before you get to that point.