Default Gnome-Control-Center Page
When launching Gnome-Control-Center / Settings it automatically opens Bluetooth Settings where the default behaviour on launch should be to open the overview titled: "Settings Page" and the parent of the Bluetooth panel, which lists all the panels. When loading from the cli using the argument -o should also point to the overview, however it is an unrecognized command in PureOS. When performing Gnome-Control-Center -l there is no default overview panel defined that we could point to.
Beware though, there is a similarly named panel called overview-info which goes to the "about" device settings page, but is not to be mistaken for the parent Settings page I am describing.