There is a wide range of mobile astrophotography apps for phones. Here are a few very useful and distinctive ones.
Polar Scope Align Pro
The best feature of this app is the surprisingly accurate Daytime Alignment. As it says this allows you to get close to Polar Alignment in the daytime. You just lay your phone on the mount cradle and adjust the Dec & Az knobs to centre the cross. Then you are really close when you do the full alignment at night.
It also has a host of other features and calculators.
Clear Outside
Reliable weather forecasts for astronomers with an emphasis on cloud cover. Features include:
Seven day hourly forecasts, updated hourly.
Low, medium, high and total cloud cover.
Moon rise/set times and phase.
Sun rise/set and transit.
Civil/nautical/astronomical darkness.
ISS pass-over information.
Automatically provides a forecast for your current location.
Save favourite locations for easy access.
Sky Safari
Very handy and cheap planetarium app that allows you to have multiple FOV indicators. Basic Version has 120,000 stars, 222 of the best-known star clusters, nebulae, and galaxies in the sky; including all of the Solar System’s major planets and moons, and more than 200 asteroids, comets, and satellites.
APT Darkness Clock
Handy free App that shows the right time to image/observe. It shows the start and end of Astro and nautical dusk and the Moon phase for selected night and location.
The APT Darkness Clock (APT DC) is a free app that doesn’t have ads. It calculates the appropriate time for deep sky astrophotography or observation in a chosen night and location. This app is a small subset of a more comprehensive desktop application called APT – Astro Photography Tool. Android & Apple
Theodolite
The app allows you to identify positions on your horizon and create a coordinate log file that can be used to build a horizon build a custom horizon for use in Stellarium