The big feature is the bubbles/heads (which is referred to as “transparent UI” in the screenshot above). I found an old quick demo of it:
I never turned it on my laptop because of limited screen space, but it was great on my PC’s multimon setup.
The video mentions a launcher for these apps, which was removed a long time ago. Instead you launched it as an application in the Start menu (or autostarted with Windows) as it worked independently from the browser as an application (albeit still chrome.exe of course). That part is normal from PWAs today, but at the time it was a big deal. According to the message I posted about before, support for the Chrome apps in Chrome itself is going away in December though.
