If you prefer to use TypeScript, React and Node as your primary technologies, I can really recommend the Yeoman generator for Microsoft Teams to scaffold your project and get you started.

Net C # for the development of Microsoft Teams Apps. But there is nothing in the way of those of you who prefer to use. Depending on what you self feel comfortable with the choice of development language. You have also a Software Development Kits (SDKs) and tools available. I will post some links to blogs and videos that are very good to get along with to be able to understand the entire development cycle for Microsoft Teams. There are samples and templates available to get you started.

But I recommend first reading Microsoft documentation on how to get started with building Microsoft Teams apps. There are many good blogs around how to develop for Microsoft Teams. You have the opportunity to develop different types of solutions / Apps for Microsoft Teams. You can read more about the Microsoft Teams App here. You can also look at Apps built on the Microsoft Teams platform as bridges between the Teams client and your services and workflows bringing them directly into the context of your collaboration platform. The Microsoft Teams developer platform makes it easy for developers to integrate their own custom apps and services to improve productivity, make decisions faster, provide focus (by reducing context switching), and create collaboration around existing content and workflows. Microsoft Teams is a collaboration platform in Office 365 that is tightly integrated with apps and services people use to facilitate collaboration to get work done together in a organization.

How to get the microsoft teams app