$ pub outdated --json
{
  "packages": []
}

$ pub outdated --no-color
Found no outdated packages

$ pub outdated --no-color --up-to-date
Found no outdated packages

$ pub outdated --no-color --prereleases
Found no outdated packages

$ pub outdated --no-color --no-dev-dependencies
Found no outdated packages

$ pub outdated --no-color --no-dependency-overrides
Found no outdated packages

$ pub outdated --no-color --mode=null-safety
Running in 'null safety' mode.
Showing packages where the current version doesn't fully support null safety.

Found no packages not fully supporting null safety.

$ pub outdated --json --mode=null-safety
{
  "packages": []
}