"without looking at their financials" does not make sense. Do they open anything in the Windows space? If a HW company wants to sell their stuff to the Linux desktop users they are generally forced to open the source, not because of good will. In terms of openness Intel does it a far away more. nVidia seems to be only exception.
Freesync comes to mind and I think they had something related to physics/hair rendering.
There is no requirement to open source on linux. Nvidia does not. It just means you have to constantly update your driver for the latest kernel version and spend time keeping up to date with all of the latest developments like wayland.
This is wrong. If you publish a Linux kernel module, you might be obligated to release the source. Fundamentally, this is how Linux differs from *BSD: Linux is intended to be generally hostile to binary blobs.
But it's not universal. Linus thinks nVidia's module may be exempt from the GPL's 'virality' because it wasn't originally written specifically for the Linux kernel.
https://yarchive.net/comp/linux/gpl_modules.html
See also https://stackoverflow.com/a/737030/