Here are a few ways you can transfer photos/videos without a computer:
1) Slower Transfer Method
After powering on the Mavic Air and connecting it to DJI GO, tap the arrow icon at the bottom, right corner of DJI GO. From there, you can choose specific photos/videos to copy to your phone.
2) Faster Transfer Method
Remove the memory card from the Mavic Air and insert it into a memory card reader that's compatible with your phone. Here are some memory card readers you could use: