It is a standardized file format specifically for recording GPS coordinates along a path/route. Many third-party applications on all different platforms can import these GPX files and display them on a map.

Yeah some niche communities that have nothing to do with extremists or politics at all are only on Twitter/X unfortunately. For example, I am into domain name investing and all my domainer friends gather on X to discuss our latest acquisitions and sales. I've tried to get people to move to Mastodon, but it's difficult.