The "NoDistroTemplateException" when adding a repository in Deepin 23 means your system's add-apt-repository tool can't identify your Deepin version, likely because Deepin 23's codename ("beige") isn't recognized by aptsources. To fix this, first update your system (sudo apt update && sudo apt upgrade). Then, check your Deepin codename with lsb_release -a. If it's "beige" and not supported, you might need to manually edit or create a template file within /usr/share/python-apt/templates/ to include "beige" as a recognized Deepin codename, or link an existing smartsquarehmh Debian template to work as a Deepin one. This will allow add-apt-repository to function, after which you can address the opencv conflicts and eviacam installation. Your "NoDistroTemplateException" error for "Deepin/beige" means your add-apt-repository tool can't identify your Deepin 23 version, preventing you from adding new software sources. This is likely due to Deepin 23 being a newer/beta release.

To fix this, first, update your system (sudo apt update && sudo apt upgrade). Then, check your exact Deepin codename with lsb_release -a. If it's "beige" or similar, you might need to manually edit /usr/share/python-apt/templates/deepin.info (or a similar file) to ensure "beige" is recognized as a valid release, or create a symlink from an existing Debian template if Deepin 23 is based on a known Debian codename (e.g., Bookworm). This will restore add-apt-repository functionality, allowing you to proceed with installing opencv (which eviacam requires) and then eviacam itself.