Serve Firebase Functions emulator with Nest application

project.json

{
  "root": "apps/api",
  "sourceRoot": "apps/api/src",
  "projectType": "application",
  "targets": {
    ...
    "serve": {
      "executor": "@nrwl/workspace:run-commands",
      "options": {
        "commands": [
          {
            "command": "nx run api:build --watch"
          },
          {
            "command": "firebase -P default emulators:start --only functions --inspect-functions"
          }
        ]
      }
    },
    ...
  },
  "tags": [
    "type:app",
    "scope:api"
  ]
}