containers.dev is a spec created and only implemented by Microsoft (in Visual Studio [Code] and GitHub Codespaces). Tool vendors (of IDEs) decided to go to war, instead of collaborating, it seems. XKCD's "standards" comic seems to apply [0] here.

As I've blogged about here [1], there are other specs such as Devfile.io or GitPod's proprietary gitpod.yml file.

[0] https://xkcd.com/927/

[1] https://www.augmentedmind.de/2022/10/30/container-based-deve...