You can upload from a mobile device or desktop PC as the AI work is done server-side. I must say it does a very good but subtle improvement.
According to the ByteXD post, in addition to fixing or restoring faces in old photos, you can also use GFPGAN to increase the resolution of the entire image. Plus, because the tool works using artificial intelligence, it can also come in handy if you need to fix AI art portraits. ByteXD provides instructions for both upscaling and improving the quality of AI art portraits, for people interested in those features.
See Use This Free Tool to Restore Faces in Old Family Photos
It's amazing how much you can learn from a clearer picture of someone's face.