This ebuild, even with 'uvm' in USE, will not automatically ensure that the /dev/nvidia-uvm device node is created. The script listed here, when created and run, will create the device node:

https://askubuntu.com/questions/590319/how-do-i-enable-automatically-nvidia-uvm

This device node is necessary for running Davinci Resolve 16 which will refuse to start without this device node existing.

There should probably be a better way to get the device node created than having to run a manual script, like via a udev rule, for example.

Once the device node is created, Davinci Resolve 16 will start correctly.