Post a 3D shot
Full side-by-side stereo — left eye in the left half. Photos (JPG/PNG/WebP), Apple spatial photos (HEIC, iPhone 15/16/17 Pro — converted here), or short video (WebM, or MP4/MOV — converted in your browser).
Pick a whole batch: the ordinary HEICs are dropped for you, and only the ones carrying a stereo pair reach the editor. iOS cannot filter the picker itself — spatial is a property inside the file, not its type. Some iOS versions still flatten a photo on the way out; if one is rejected as 2D, use Photos → Share → Save to Files, then Browse → Files.