I can live with some of the missing features:
No noise cancellation
Audio devices are configured via windows sound settings
Can only share full screens and not individual windows
Standard Windows notification sounds and not the Teams sounds.
Maybe missing more otherwise its more or less the same app.
I've installed it as a Chrome App and it has its own window, task bar icon / shortcut and generates notifications.
I'd suggest others to try it out.
I was about to get a second device for teams. Performance has degraded so badly that it's now impossible to pretend to be in a meeting and run an IDE / office apps / factorio at the same time.
At least on Chrome, the Teams screen sharing option summons the Chrome screen sharing dialog, which allows you to select either the whole desktop, individual windows or specific tabs inside the browser. Maybe the limitation is from the browser you are using? (Although I would be very surprised)