Android: Get native HardwareBuffer Format (ImageFormat.PRIVATE)

Question

I'm trying to figure out if I can use the HardwareBuffer.USAGE_GPU_SAMPLED_IMAGE flag in my ImageReader constructor:

val format = ImageFormat.PRIVATE // or ImageFormat.YUV_420_888
val imageReader = ImageReader.newInstance(
  width,
  height,
  format,
  MAX_IMAGES,
  HardwareBuffer.USAGE_GPU_SAMPLED_IMAGE // <-- this one
)

To find out if that is supported, I am using the HardwareBuffer.isSupported method:

val supportsGpuFlag = HardwareBuffer.isSupported(
  width,
  height,
  ???, // <-- what do I put here?
  1,
  HardwareBuffer.USAGE_GPU_SAMPLED_IMAGE // <-- check if GPU is supported
)

I am usually working with ImageFormat.YUV_420_888 images, but there are some applications where I can switch to ImageFormat.PRIVATE images which makes the pipeline significantly more efficient.

I guess ImageFormat.YUV_420_888 is equivalent to HardwareBuffer.YCBCR_420_888, but what is ImageFormat.PRIVATE equivalent to?

On my emulator I tested streaming PRIVATE images and check their HardwareBuffer format which yielded HardwareBuffer.RGB_565, but I'm guessing this is different from device to device and is probably HardwareBuffer.YCBCR_420_888 on most devices.

But how do I get that at runtime?

TL;DR: I want to get the HardwareBuffer format equivalent of ImageFormat.PRIVATE flag at runtime.