Depth resolution on the iPhone's rear cameras is marginally better at 768 x 576, but the high res photo resolution is also larger at 4032 x 3024. So on the iPhone depth is 1 : 5.25, while on the iPad front camera it's 1 : 4.825. Note that the above console output lists the iPhone depth as 768 x 432, but the size of the captured image from the sample code is actually 768 x 576.

I bought an iPhone 12 Pro today and both builtInDualCamera and builtInDualWideCamera report supporting depth. This leads me to believe that the iPad dual wide camera should also support depth and hopefully this issue is just a bug. <AVCaptureFigVideoDevice: 0x11fd368e0 [Back Dual Camera][com.apple.avfoundation.avcapturedevice.built-in_video:3]> supports ['dpth'/'hdis' 160x 90, { 1- 30 fps}, HRSI: 768x 432, fov:38.784, 'dpth'/'fdis' 160x 90, { 1- 30 fps}, HRSI: 768x 432, fov:38.784, 'dpth'/'hdep' 160x 90, { 1- 30 fps}, HRSI: 768x 432, fov:38.784, 'dpth'/'fdep' 160x 90, { 1- 30 fps}, HRSI: 768x 432, fov:38.784, 'dpth'/'hdis' 320x 180, { 1- 30 fps}, HRSI: 768x 432, fov:38.784, 'dpth'/'fdis' 320x 180, { 1- 30 fps}, HRSI: 768x 432, fov:38.784, 'dpth'/'hdep' 320x 180, { 1- 30 fps}, HRSI: 768x 432, fov:38.784, 'dpth'/'fdep' 320x 180, { 1- 30 fps}, HRSI: 768x 432, fov:38.784] <AVCaptureFigVideoDevice: 0x11fd36ef0 [Back Dual Wide Camera][com.apple.avfoundation.avcapturedevice.built-in_video:6]> supports ['dpth'/'hdis' 160x 90, { 1- 30 fps}, HRSI: 768x 432, fov:70.291, 'dpth'/'fdis' 160x 90, { 1- 30 fps}, HRSI: 768x 432, fov:70.291, 'dpth'/'hdep' 160x 90, { 1- 30 fps}, HRSI: 768x 432, fov:70.291, 'dpth'/'fdep' 160x 90, { 1- 30 fps}, HRSI: 768x 432, fov:70.291, 'dpth'/'hdis' 320x 180, { 1- 30 fps}, HRSI: 768x 432, fov:70.291, 'dpth'/'fdis' 320x 180, { 1- 30 fps}, HRSI: 768x 432, fov:70.291, 'dpth'/'hdep' 320x 180, { 1- 30 fps}, HRSI: 768x 432, fov:70.291, 'dpth'/'fdep' 320x 180, { 1- 30 fps}, HRSI: 768x 432, fov:70.291]