Microsoft Dev Box cloud-based development environments

Microsoft Dev Box, a new cloud service that provides developers with secure, ready-to-code developer workstations for hybrid teams of any size. Microsoft Dev Box empowers developers to focus on the code only they can write, making it easy for them to access the tools and resources they need without worrying about workstation configuration and maintenance. Dev teams preconfigure Dev Boxes for specific projects and tasks, enabling devs to get started quickly with an environment that’s ready to build and run their app in minutes. At the same time, Microsoft Dev Box ensures unified management, security, and compliance stay in the hands of IT by leveraging Windows 365 to integrate Dev Boxes with Intune and Microsoft Endpoint Manager.

from Microsoft Tech Community - Azure Developer Community Blog - Introducing Microsoft Dev Box - May 24, 2022

Blog post covered e.g. in Ars Technica - Microsoft Dev Box will virtualize your Windows development PC in a browser window - May 25, 2022

I've written before that just getting a development environment set up with all the necessary supporting libraries and dependencies sorted out is a major barrier to casual development these days, and that language-specific cloud services such as Google Colaboratory for Jupyter Notebooks help address this.

Additionally in a corporate environment there are often rights restrictions that limit the end-user's ability to install and manage software, which can make it difficult to maintain a complex software development environment. 

Pre-packaged virtual machines in the cloud offer a potential quick path to productive development environments.

This may also help scientific researchers who may want to do software development but have neither the time nor expertise to install and configure a complete environment themselves.
Additionally as MS indicates, this means access to a full Microsoft development environment even if your underlying platform is macOS or Linux.

because Microsoft Dev Boxes are hosted in the Microsoft cloud, you can access them from anywhere: Windows, MacOS, Android, iOS, or your web browser

Microsoft Dev Box has Microsoft 365 integration (unsurprisingly) which may also make it an easier fit for corporate environments.

Currently in private preview, public preview coming "in the next few months".