I am running Ubuntu 23.04 on Gigabyte B450M DS3H WIFI-CF. I got errors trying to add the apt repository:

404  Not Found [IP: 185.125.190.52 443]
Reading package lists... Done
E: The repository 'https://ppa.launchpadcontent.net/thopiekar/openrgb/ubuntu lunar Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

I had to download the app image and install libfuse with sudo apt-get install libfuse2; after that, I had to grant execution permissions and execute sudo with the following commands to launch the application:

$ chmod +x Downloads/OpenRGB_0.8_x86_64_fb88964.AppImage
$ sudo Downloads/OpenRGB_0.8_x86_64_fb88964.AppImage 

Attempting to connect to local OpenRGB server.
Connection attempt failed
Local OpenRGB server unavailable.
Running standalone.
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-root'

Change the mode and click any color other than black to see the light change. You may get a prompt to enter the number of LED lights at launch. I entered 50 as I have about 50 LED lights on each strip. Exiting the application does not kill the lights!