Hi,
To begin, the best option is to consult the documentation of Teams Platform available here.
Basically, all the capabilities that a developer can use to extend Teams are based on a web app or an API, and there are no specificities, even if you are in Teams. Based on that, you can host your front and backend on the platform you want. The only requirement to use Azure is to declare Azure Entra App ID to enable SSO with a Microsoft Account or declare a Bot to connect your backend with Teams.
Your front and back can be separated and also on a different URL.