Fix 'VCHI initialization failed' on ubuntu pi:
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The use of the vcgencmd command will fail with a standard ubuntu arm install. You must add your user to its group by:

sudo usermod -aG video <username>
*Replace <username> with your user or who ever you want to use the vcgencmd command
You will also need to log off then back in for it to take effect.

Source: https://chewett.co.uk/blog/258/vchi-initialization-failed-raspberry-pi-fixed/
Date: May 7th 2022