Hi
I have a usb hard drive containing my pictures. Hass.io is running on a PI3 and can be accessed from the internet by DuckDNS. If I connect the Hard Drive to the USB port of the PI3, will it be possible access the pictures through HA. How?
Not really. HA isn’t intended to be a file sharing platform.
HA can serve up pictures/files to people, but it isn’t a file sharing service.
Anything you put in <your_config_dir>/www is publicly accessible at domain.tld/local
You can use this if you want to share an image after an automation (capture a photo when someone is at the door, and send a link to someone so they can see or process the picture.
If you want to host a photo gallery, then you are better off using something like http://piwigo.org/
You could check out this add-on
https://community.home-assistant.io/t/new-addon-samba-nas-mount-external-disk-and-share-it/172193/57