Apple - Set maximum audio volume on macOS?
If you're still on the hunt for such an application, I have great news. I wrote a simple status menu bar app, which lets you limit the main output volume of your Mac. The app is called Earsafe, check it out if you have time.
All the best!
I had a similar issue and it was solved (not intentionally, just a happy by-product) by using a 3rd party media player.
In my case, I used Vox. It has it's own volume control which I set at a level that no matter if the system is set to "max" it won't be any louder than what is set in the app.
The best part is Vox is free (as in beer).
So this solves my clumsy typing problem, but it does not answer my question of limiting maximum audio volume.
I went into System Preferences > Keyboard and tapped the "Customize Control Strip..." button. From there I dragged the volume slider from my touch bar to the "Remove from touch bar" area.
Now I have greatly reduced my chance of accidentally engaging that control and then inadvertantly swiping right dramatically. And now that I think about it, I'll remove Siri from a nearby spot also.