> And for the question on scrolling: let me press an additional button that enables scrolling with the ball, both horizontally and vertically.

I mentioned this in another comment, but on macOS, there's a utility called SteerMouse (http://plentycom.jp/en/steermouse/index.html) that apparently supports chording for scrolling with the ball and is compatible with a number of different trackballs.

Sadly, I've found that that particular feature isn't working properly on Catalina with my Huge, but I contacted the dev and he said he's looking into it. So fingers crossed...