There are multiple ways to deploy a scoped application to a target instance:

• Publish the application to an update set (Official documentation)
• Publish the application to the application repository (Official documentation)
• Use the OOTB available Git integration (Official documentation)
• Use the Now SDK for both development and deployment (Official documentation)
• There is an OOTB available application for this purpose, called ReleaseOps (Official documentation)

I have already used all of these solutions, and I would say that selecting the right approach heavily depends on the development team's maturity level.

The simplest way is the "publish to update set" approach. Based on what you wrote, I would recommend this one.

Using the application repository is also a good option, but you need to understand how it works, how you can deploy the app. This approach is not as flexible as using update sets (e.g. managing hot fixes).

The best thing you can do to start with the following training: Application Development Fundamentals