What is `”dev” true` in package-lock.json for?

So answering your first question, "dev": true in package-lock.json means this dependency won’t be installed by npm install/npm ci when running in production mode.

Having dependencies used only for local development environment marked with "dev": true and then using --production in your CI might save you some build time.

From documentation https://docs.npmjs.com/cli/install#description:

By default, npm install will install all modules listed as
dependencies in package.json.

With the --production flag (or when the NODE_ENV environment
variable is set to production), npm will not install modules listed
in devDependencies.