Following How to extract depth map from .heif image created with iphone X using imagemagick, I can extract the depth map as a byproduct of heif-convert. This produces an image with the blurred data and an image (half-size) of the depth map. The Apple Photos app has a feature to /disable/ the 3d blur, implying that either the blur is reversible (unlikely?), or the non-blur information is intact.
$ heif-convert IMG_0050.heic IMG_0050.jpg File contains 1 images Written to IMG_0050.jpg Depth image written to IMG_0050-depth.jpg