Given this configuration:

// nx.json
{
  "targetDefaults": {
    "fun": {
      "executor": "nx:run-commands"
    }
  }
}

// project.json
{
  "targets": {
    "fun": {
      "options": {
        "command": "rimraf /"
      } 
    }
  }
}

Knip reports rimraf as unused:

Unused devDependencies
                   
rimraf              package.json

Because it requires an explicit executor:

https://github.com/webpro/knip/blob/1ecdf800329dd9850771cbf270f451f85cff50b8/packages/knip/src/plugins/nx/index.ts#L56

I would propose just dropping .filter. I understand that it makes the heuristic more loose, but in reality, even when there's overlap with non-nx:run-commands executors, it's still semantically close enough. The only overlap in official executors I found is in @nx/remix:serve, and it would actually be good to consider it too.