Local image or icon not shown for mobile notification in Android

Configuration
1

Looks like internet URL’s are working but local files aren’t, for both image and icon_url.
Here is a sample configuration that isn’t working:

service: notify.mobile_app_device
data:
  title: Some movement
  message: "my message"
  data:
    icon_url: "/local/icon/siren_white.png"

But the following does work (as an image, not an icon, but that’s probably another issue):

service: notify.mobile_app_device
data:
  title: Some movement
  message: "my message"
  data:
    icon_url: "https://www.pngfind.com/pngs/m/2-25271_png-file-police-siren-icon-png-transparent-png.png"

The same happens when using image notion
I verified the local URLs are valid (adding a picture entity with this path)