Ok, well I appreciate what you are saying however, its um wrong in this case.
I previously had Linux Lite 5.8 on the system.
LL 5.8 gave me the option to install the proprietary nvidia drivers. Version 340.108 is [last version to support the card] [
https://www.nvidia.com/Download/driverResults.aspx/156163/en-us/ ]
I used those drivers and was able to run hardware h.264 decode from several streaming apps and use VLC to test with.
I think you may be thinking about the requirements for hardware ENCODE.. [something I would not dream of trying on this old box]
I was also able to run steam games [direct x using proton] at a almost decent frame rate. [25-40 fps]
I was able to use the steam streaming function which used the H.264 decode.
Moonlight [similar app that streams from the nvidia card on the server side] also worked fairly well.
I may have to see if I can find a manual way to install the driver, I tried "sudo ubuntu-drivers autoinstall" but that did not work..
Unfortunately without access to the proprietary driver like LL 5.8 had much of this does not work.
I salute the nouveau project and they have done some amazing things but its still a bit behind the proprietary driver.
[https://nouveau.freedesktop.org/VideoAcceleration.html]