App First, Platform Later
As Apple platforms unify the user experience and underlying technologies, we need to change our approach to making apps.
Instead of designing for, say, iOS and then expand to macOS later. We need to think about universal design and experience in our applications and then adapt it as required for each platform while retaining as much of the core design and idea as possible on all platforms.
Not only does this give a more natural feel to the user when they move from platform to platform, but it also enables us to think about feature parity. If we have the features on every platform, we can then give more thought to the UI's implementation if needed for a particular part as appropriate.
We are starting to see applications running on various platforms in ways that we had not imagined until now. iOS applications are running on Macs with the new Apple silicon, for example. We have to adapt our thinking and planning to allow for the possibility that our applications operate in ways we had not anticipated. Spending more time making sure our interfaces work nicely beyond our intended device or audience will enhance the experience.
There is another aspect that will become more important as we move forward.
Data syncing, users will expect that if an application exists on more than one platform or device, they should see their data or files on all those devices. For example, writing applications should make documents available for the user whenever they want to continue working.
When I evaluate an application used to create content of any kind, one of the primary things I check is to see if I can work on more than one device. I want to work on my iPhone, iPad, Mac, and even Windows depending on the need in an ideal situation.
At the very least, I expect to use my Mac and iPad as primary work drivers when I'm blogging or creating podcasts, for example.
Take these thoughts into account when you create a new project or consider adding to an existing one. Your users will thank you for it.