Excerpt from email thread with :mbalfanz about UX considerations for desktop zoom:
Provide keyboard modifier for scroll wheel:
This one is a bit trickier. It would be great to introduce a keyboard modifier for mouse support!
We will need to select the right modifier key. As far as I can tell, on Mac both ctrl and cmd trigger reflow zoom. On Windows, only ctrl does. I'm no Windows user, so please somebody correct me here. One suggestion could be to use opt+scroll on Mac, and alt+scroll on Windows.
Looking at the prefs, macOS does indeed map both ctrl and command to reflow zoom. Maybe command can be repurposed. Opt/alt+scroll is already in use for page navigation on both Windows and Mac.