Apple Live Photos are a pair of a still image (.JPEG or .HEIC) and a video file (.MOV). Non-Apple phones can generate these same types of images but when importing to Photos, they won't be associated together as a Live Photo pair and will be imported as separate images. Live Photos have a metadata Content ID tag that must be present in both the image and the video so Photos knows the two are a pair. Unfortunately, the usual tools like exiftool cannot write this metadata tag because it's in a proprietary format (a so-called "Maker Note"). I've created a free open-source command line tool, makelive that writes the tags to convert images and videos into Live Photos using the native Apple API for doing so, thus it's able to write the proprietary tag. There are installer packages for both Intel and ARM on the releases page.