Anything else to explain besides the name?

gnome-terminal-new-tab-in-existing-window [any additional options here]

This flimsy wrapper behaves like gnome-terminal --tab ..., but opens a new tab in the existing window if possible. Any options are passed directly to gnome-terminal.

It does nothing more than set two environment variables, GNOME_TERMINAL_SERVICE and GNOME_TERMINAL_SCREEN.

• busctl
  • Get current bus name and screen ID of gnome-terminal
• Activate Window By Title (GNOME Extension)
  • Activate the existing window after a new tab opened
  • Supports both of X and Wayland, maybe
  • This extension seemed to be easier than to use the portable one