God yes, I hate how all FEs have tunnel vision on MacOS nowadays. Our sign-up flow had godawful scrollbars both horizontally and vertically for the longest time but they didn't notice because they're all on retina display Macbooks instead of what the bulk of our users will be using.
Macos do have a option to always show scrollbar. And I think this is a pre-requirement to enable that if you ever care about what your user may actually see as a FE.
Besides that, there isn't actually obvious different between firefox/chrome/edge on macos/windows.
The most problematic one is actually safari(which is on mac only). If you dev on chrome and use on firefox or vise versus. You usually get a "mostly work with minor visual different". But safari… will give you a fail and are't even usable. It is outright the modern age ie.
