You can use The Ansel tool from NVIDIA to capture 360 photos in supported games.
Press Alt-F2 in a supported game to capture the image.
Set Capture to 360 Photo Sphere.
Set Resolution to 4096 x 2048.
If you accidentally use the stereo option you will need to crop the image in half horzontally.
You can use the following link to view some 360 captures. Unfortunately it's not easy to download these images but they highlight the games that Ansel supports. https://www.nvidia.com/en-gb/geforce/shot-with-geforce/