Microsoft Endpoint Manager adds management and compliance checks for Linux desktop

bdam55 : this was probably a simple example for illustration purposes.  As you can see in the screenshot, there is a .deb file on the desktop, which is most likely the Company Portal app, acting as an identity broker and token manager, just like it is on Apple Macs. And a 2nd part not presented here, the Edge for Linux browser talking to the broker (to fetch the AAD DeviceID for example), and send it during the MS authentication phase.

As for the browser things : while Edge for Linux is most likely released with a MS plugin, that can interact with Company Portal, I don't know how this will be handled in Chrome and Firefox on Linux.  Firefox 91 added some code to SSO with your Work or School Account on Windows OS, so I guess someone at Mozilla will have to port that feature to Linux as well (maybe it will even work out of the box, who knows...).