The idea is to support Linux desktops like Ubuntu and Fedora. Currently, only the web client is available for Linux, but many features are not available.
Just wanted to add my 2c worth here as well; While the web client works for connecting, its performance is noticeably worse than the Windows App.
When running Teams on the virtual device or cloud PC it cannot be optimized since the web client on Linux lacks the WebRTC Redirector/Teams media-optimization pipeline that Windows/macOS/iOS/Android get. Audio and video is laggy because the encoding/decoding cannot be offloaded directly to the local hardware