Is this possible? I understand will need to open port on firewall.
Duplicati itself does not act as a listener for incoming backups. But depending on where you are running Duplicati, you may be able to configure incoming backups using another service running on that same device.
For example I have a Synology NAS which backs up itself using Duplicati to cloud storage. But this same NAS is a Duplicati backup destination for some of my family’s computers. I installed a WebDAV service on my NAS although that’s just one way to do it.