[NOOB question] failed to launch chromium from CLI "Failed to put Xlib into threaded mode"


From a fresh dietpi on my raspberry pi 3 b+, I install chromium without issue in the aim of running it at start (without using a desktop since my application required only a web browser with multiple tabs) however I can’t even launch it from the CLI.
I got this message “Failed to put Xlib into threaded mode” and “Gtk-WARNING **: cannot open display”
Raspberry is connected to an hdmi screen.

Any idea ?