Unset QT_PLUGIN_PATH When Accessing Non-NixOS Host xdg-open or QT applications

[alastortenebris]

Describe the bug

When opening a QT application on the host system from Nix, the application will crash as it cannot find the QPA plugin.

Steps To Reproduce

Open a QT application installed in a nix profile (Calibre in my case). Try to open another QT application on the host system (Dolphin in my case).

Expected behavior

The app runs.

Metadata

nix-env (Nix) 2.34.7 (Fedora 44 Kinoite)

Additional context

QT_PLUGIN_PATH needs to be unset for QT applications on the host system to run properly.

Checklist

• checked latest Nix manual (source)
• checked open bug issues and pull requests for possible duplicates

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[xokdvium]

Tbh this doesn't sound much like an issue Nix is usually concerned with. Graphical applications are a whole can of worms on non-NixOS (see e.g. https://github.com/nix-community/nixgl) and Nix has zero visibility into those. Environment issues also can't really be handled with nix, since from nix's PoV store objects are mostly plain old data.

Maybe this might be more of a nixpkgs issue?