NVIDIA card not completely off?

[ratcashdev]

Not sure if this is the best place to ask, but if not please direct me to the proper place.
I am using optirun intel-virtual-output -b to use the external monitor on my Thinkpad X1 Extreme wired to the HDMI port (which in turn is connected to the Nvidia GTX 1050 Ti card). Utilizing the proprietary NVIDIA driver with bumblebee.

Doing pkill -9 intel (i.e. KILLING it, forcefully) will seemingly power down the card (cat /proc/acpi/bbswitch shows OFF), but strangely, the SUPER+P combination in GNOME will still show me the JOIN DISPLAY options. Also disconnecting/reconnecting the external monitor also is recognized by GNOME (the JOIN DISPLAY options shows up for a second).
Issuing tee /proc/acpi/bbswitch < ON and afterwards tee /proc/acpi/bbswitch < OFF has no effect.

On the other hand doing pkill intel (i.e. just TERMINATE, no KILL) will properly close down the external card. However, bbswitch will show OFF, but the SUPER+P combination does not show up the display join options any more and disconnecting/reconnecting the cable does not seem to be detected by the system any more - as if the NVIDIA card was more OFF than before.

Is there a way to really doublecheck if NVIDIA is still running/powered on? lsmod |grep nvidia returns empty results in both cases.