Trusted Web Activities are a mode of Chrome Custom Tabs without browser UI, available to web content an app developer controls. We want the modern mobile web (primarily PWAs) to go mainstream. Nevertheless, they make up a small proportion of app experiences on Android today. The vast majority of developers simply haven’t made one yet. TWAs lower the risks of distribution by allowing developers to integrate their PWA into a native app and give PWA developers the same capabilities as native apps.
Docs: https://codelabs.developers.google.com/codelabs/getting-started-with-twas/index.html https://developers.google.com/web/updates/2019/02/using-twa