I learned recently that Teams (Windows) does have a handler for webexteams:// URLs and it is possible to create a link to a specific space (although not easy since it requires finding the space id). However, Teams does not support links with schemas other than http:// and https://, which means the URL would have to be posted as plaintext and copy/pasted into a browser (or distributed through email, posted on a website, etc.). Additionally, when creating a link in a Teams space using markdown format with a schema other than http or https, the display text will be shown but it will not be a clickable link.
This request is two-fold:
First, allow links in Teams for additional schemas; not just webexteams:// but also onenote:// and other popular application-specific schemas.
Second, make it trivial to generate a link to a space or a message (an option under the space menu and a button on the message hover toolbar).
In all cases, links to spaces and messages would only work for members of the target space. Others would receive an error stating they do not have access to the space.