There’s some culture clash there because Duplicati’s commandline tool wants all its options on its invocation.
What you’re asking for might be a command line tool that can do things GUI-style except not using the GUI…
Integration between command line and web interface #2693
and there’s a proof-of-concept, but I’m not sure about current status or future plans. You can ask @Pectojin
You could add your use on the GitHub thread or Client-side agent and centralized management / dashboard