Orca supports importing GPX files. GPX Waypoints will be saved as Spots, while GPX tracks will be saved as routes. To import GPX file into Orca:
iOS and Android: From the application you want to share from, share the GPX via the standard share menu and select Orca as your share destination
MacOS: Right-click the GPX file and select Open With > Orca
GPX export is currently not supported but will be added in a future release.