How much can she do on a 1GB?

This is what I'm getting her

Are you talking about 1GB of data or storage? Those are 2 different things.

For storage that's quite low. Does the phone have the option to expand with a memory card?

For data she can get by with 1 GB if she connects to wifi most of the time. SNAP, IG, Messgener and other apps would use data from her provider unless she's connected to wifi and really only use any significant storage if she's downloading and installing pictures, videos, etc to her device.

2.5 GB free space on your phone's memory is required to install the game with all of the downloadable content. What smart phone do you have that only has 1 GB memory? My ancient iPhone has 16GB and the newer models have 512GB. Some Android phones have a full terabyte of storage space (i.e., 1000 GB).

If you're asking about data use, most people are on WiFi throughout the day, so it only matters on a road trip.

From what I saw, it take 1.08 GB to download the game.