Developer here, why wouldn't you just install the official pip package `ddcci-plasmoid-backend`?

I personally avoid using pip for managing system libraries because they often end up conflicting with distribution provided packages. Even if packages are missing upstream, they often pull in dependencies that may end up conflicting later. Versions start mismatching, tools stop using when sudo gets involved, all kinds of weirdness that's hard to debug if it's caused by a library you pulled in months ago.

My workaround for this problem is to install these tools in a separate venv and calling the binaries with their full path, but for tools like this where the command is built into the program that may be more difficult. It's also a waste of space in some cases, though deduplication tools can help there.

I get your point. At some point this widget provided an option to specify the backend command manually, though I removed it because I couldn't see any use cases. I would happily add this functionality again if you require it.

I was just explaining why people like me don't like using pip as a system package manager, I'm not trying to turn this into a feature request :)

I have my solution and I think many others have their own. In my opinion it's perfectly fine to just state "platforms that don't have the necessary packages in their system package manager aren't supported, use at your own peril" so niche distributions making up the long tail of your users don't end up taking unreasonable amount of support and development time.

I never use pip for the system site-packages, that's the job of the distro package manager.

As for pip install --user, I sometimes nuke the local repo so wouldn't be a robust solution given my workflow.