Regarding the aesthetics, are you serious? The Windows version feels like a dinosaur in comparison to the macOS version.
As for the startup times, maybe it has to do with Intel?
Microsoft wasn't able to bring
ActiveX support to other platforms.
Besides, it's
extremely ancient.
Nobody should be using ActiveX in 2022...
I am serious about aesthetics, but everyone likes different things. Microsoft puts the most efforts into their own platform. Try typing in Word. The cursor is subtly animated, moving smoothly ahead of the typed characters. The ribbon even animates its reorganization when the window resizes. You might not care about such things, but I find them very pleasing.
Microsoft seems to be doing its utmost to make the Mac versions look just like the Windows versions, so I don't understand how one feels like a dinosaur compared to the other. (I assume we're both talking about the latest and greatest Office 365.)
Excel documents tend to be very old in my line of work. They have ActiveX controls in them. I suppose a new document shouldn't introduce such things if it had to be cross platform. But, say you wanted to put a checkbox on a sheet. You are presented with two options: "Form Controls" and "ActiveX Controls". The ActiveX checkbox just looks nicer; it's so easy to make the wrong call. Excel doesn't help you choose.
You seem to be saying that no one should be using ActiveX in 2022, so don't worry about it. But I still think it's worth mentioning to the OP as a potential stumbling block. Only the OP will know if ActiveX is in use at their organization.
I did a random experiment of putting an Excel spreadsheet inside a Word document. It's a complete triviality and works perfectly on Windows; the Excel document can be edited from right within Word. On the Mac, Excel has to launch separately to work on the contents. No big deal unless the user finds it awkward, and it happens to be a common occurrence on the documents being worked on.
Due diligence before pulling the trigger, unless it's easy to switch back to Windows later if the Mac versions turn out to be problematic or just annoying.