I heard about that a long time ago, back when it looked kind of dead. Glad to see it's still under development. I'm skeptical though, does it actually support all of Slack's features (or even a majority of them)? The screenshot is rather minimal, showing nothing in the way of unfurls, no formatting beyond a link and an @mention, no userlist, no channel info, no pinned messages, no reactions, etc.
Or because they are unaware that there are native apps available, just from third parties. For example: https://volt-app.com/