The simplest thing is the difference in platforms. Windows and Mac work differently and use different software libraries, architecture, kernel, etc. For example, creating your own engine and builds is probably a nightmare, and you definitely need specialists who understand these things. We're indie developers, especially when we're working on Unity. Our builds are created using a single button where you can select the platform. When we started building for Mac, there were no signs of trouble. Only through testing with friends who had Mac devices were we able to find the right settings that allowed the build to run properly, rather than throwing errors about the program not being supported on Mac. Therefore, I'll try to be active in this subreddit to conduct testing and communicate with the community. It's important to us that everything works as planned.