You can't use Gitpod, Theia IDE, etc with Pylance. Or GitHub Copilot. Or Live Share or numerous other VSCode extensions.

The idea is people start a project in VS Code, need to scale up to a reproducible dev environment for multiple users, and follow ads in VSCode to GitHub Codespaces, which charges by the hour for VMs. Now you're locked into that, you're locked into GitHub as well, and they can cross sell you GitHub Actions, GitHub Advanced Security &etc.

Therefore, Pyright is almost the minimum needed to add type checking to your CI process.

Edit: to clarify, not only is Codespaces advertised in VS Code, it also uses private APIs so no competitor can publish an extension which replicates this functionality on the VSCode marketplace.