This gets asked every once in awhile, but as with all things openHAB it would require a developer to have interest in the project. Unless that occurs, there will be no plans to develop a Wear OS app.
This also seems to be the case with the Apple Watch (which I believe has a much larger user base than Wear OS).
I have a Galaxy Watch 4, and I set up Tasker and WearTasker to send commands to items. But I never found a good reason to use this functionality, as I instead just use Google Assistant.
I haven’t tried this, and I don’t know that I’d trust it.
This is similar to what I was doing.
Why not just make your openHAB items available to Google Assistant?