Describe the bug

This flag applies to many commands, but not some, such as nix store gc

EDIT: We may choose to keep ignoring the flag if we decide that's ok, but that should be part of the larger discussion about global flags; can be out of scope for this issue. The main problem is with the help text / docs.

Steps To Reproduce

nix ... --help

Expected behavior

Show relevant options.

nix-env --version output

Additional context

• nix store gc: Stabilize #7608
• Triage and break up the global settings #5638

Priorities

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