Sure. But certainly there are gel tests that show penetration through flesh. There are likely some with barriers, as well.Good point, and more importantly, can't say it does/will work, without some data there as well.
And you can test shootability/accuracy/speed between it and larger calibers.
And you can logic that 9mm isn’t much larger than 5.5mm in comparison to the size of a bear.
All of that would seem to paint a picture of it being a viable, if not good, option.