https://wccftech.com/microsoft-kills-project-catnip/

Microsoft has announced that it is halting Project Catnip, a Progressive Web App (PWA) for Windows Insiders. The Windows maker has cited "technical limitations" behind this decision, but added that it continues to explore other options. The company made this announcement while releasing the latest Windows 10 Preview Build:

We’re no longer planning to do external testing or a public release of our “Project Catnip PWA” for the Windows Insider Program. Due to some technical limitations, we were not going to be able to offer the experiences we wanted to for Insiders through the PWA. We’re still looking at solutions for some of the features we investigated in the PWA. Thank you as always for your enthusiasm.