WebContainers: Dev environments. In your web app 2 years ago
StackBlitz has always struck me as a solution in search of a problem.
Buyer beware: WebContainers is closed-source and there are hundreds of open issues from users. Most of them are ignored for weeks and months at a time as the company pivots from one thing to the next: https://github.com/stackblitz/webcontainer-core/issues