Kind of a hilarious take if you watch the keynote where significant time and a moving backdrop are devoted to highlighting the miasma of navigating across 100 apps on a smartphone. Decrying "just install another app" is a big part of the raison d'etre for the whole product!
Yeah the "OS" appears to be their backend that boils down to your login credentials + something like Selenium WebDriver + ChatGPT. The R1 device is just a thin client.