There is an IOS app for hot air balloon pilots called "Hot Air". There is a similar app for Android that... Leaves much to be desired.
There's several functions that are needed. First, we need a map. We need to be able to enter waypoints and/or polygons charting landing zones, prohibited zones, targets, etc. we need an easy way to select targets, and our bearing and distance to those targets.
For planning purposes, we need a bearing line that we can place and move on that map. We need to be able to easily drag and drop each end of the line, and get the bearing and distance between the endpoints.
Next, we need track recording. It should record a ground track during flight, preferably with altitude information, and notes about the flight.
Next, a wind map. The wind speed and direction varies considerably by altitude. It needs to record direction and speed as we climb and descend, telling us what altitude has winds favorable for our current target.
Bonus points if we can prepopulate that wind map with data from a "pibal" (pilot balloon; a simple latex party balloon released and tracked with compass and stopwatch before a flight)
Next, coordination with other pilots and ground crews. 3D location sharing between participants; wind map data shared between pilots.