Your solution should work, if you don’t need the buttons to have a max width, so thanks for that. Another one I have thought of is to wrap the buttons in groups with the desired minimum margins between them, and have the groups shrink instead.

To be clear though, I didn’t make this post for help with any particular app. The demonstration app I linked was just the easiest way to demonstrate my point, which is that it seems bizarre to me that bubble designed responsiveness this way.