As of now, Screen Sharing on Teams doesn't work for Microsoft Teams on Wayland-based Desktops. As Pipewire is the API that newer Linux desktops, which is provided on Electron 12+ (which I think you are using for Teams App), which can I think be enabled by a configuration flag, which should work with relative ease, as Electron 12+ supports Pipewire Sharing (under a chromium flag).
We'd love it if you officiallytake over the present Flathub App by yourself. As far as I've seen, the community have made available a wrapper for Flatpak which essentially uses the official DEB installer behind-the-scenes to work. Since many Linux stores/software centers directly rely on the Flathub store, where everything else is managed by Flatpak, it would be nice if you'd maintain the Flathub Entry (along with timely updates), so as to provide a seamless Microsoft Store/Mac App Store like cohesiveness for Linux, but with a more open approach.