Thinkpad to iPad Pro w/ USB-C as second monitor
 

I thought I had every cable, adapter, and dongle under the sun.

A second monitor would be soooo helpful for what I'm about to do for my next deadline.
Family visiting for Christmas is sleeping upstairs in my study, so my multi-monitor setup there doesn't help.
I thought - no problem, I've used Duet before with my same Thinkpad and my old iPad Pro w/ lightning connector, and it has worked perfectly.

However, now I have the iPad Pro with USB-C. Duet is not recognizing it. I searched their FAQ and Getting started - no answer there.

I have these cables:
Apple's USB-C to USB-A (female)
USB-C Digital AV Multiport Adapter
However, to plug it into my thinkpad I needed to find a USB gender changer to go from the USB-A (female) to what I need, USB-A (male).
Net: Still didn't work.

I suspect the gender changer is the problem.

So I looked through my USB-C box to find a single cable that is: USB-A (that is also USB-3) male to USB-C
I don't have that! I thought for sure I had one.
I do have several that are like:
Apple's USB-C to USB-A (female)
but I can't plug a USB-A female cable into my Thinkpad's USB port. Gah!

Then, I looked on Amazon to find a single cable that is: USB-A (that is also USB-3) male to USB-C that supports Thunderbolt.

Based on that google engineer who initially exposed all the big problems from bad USB-C cables:

i'll probably go with this one:

When I initially searched, I didn't see any hits because I added "Thunderbolt" to the search.

If you're anywhere near a Micro Center, you could also run there and grab something to try (and return if it doesn't work).

Have you used the Duet app? Works perfectly for most things.

To get any device with a screen with an USB C port to function as a monitor attached to a host with an adequate(!) USB C to USB C cable somehow the pixels need to get from the host generating them to the panel of the device. Either they travel as a video signal or instead they travel as data in a proprietary format where an application on the host generates this data stream and the other half of the application on the device copies the pixels out of the data stream to the display. The former .. doesn't exist? In older tablets people were like "hey, look, a HDMI port, why does this not work as a monitor?" and now they are like "hey, look, a USB C port, why does this not work as a monitor?". Even the otherwise very notable upcoming Dasung notEreader (eInk ereader, Android tablet, mini field monitor) doesn't present itself as a USB C monitor to the world, it sports a HDMI port for this purpose. Anyways, Duet does the latter over USB already, with the Lightning port carrying the USB signals. if it doesn't work with USB C I would expect they will fix it soon if the iPad Pro provides the necessary capabilities. iOS is a very closed system so who knows what's going on there. Duet would need to instruct the USB C port to become an Upstream Facing Port and if Apple doesn't provide a mechanism for this then you are SOL.