Apple has always denied that merging its mobile and desktop operating systems, the way that Microsoft has done, is a good idea. But from 2018, it is reportedly starting to explore that road by giving developers the ability to create apps which work on iPhones, iPads, and Macs.
Depending on the hardware you use them on, these apps could be controlled via touchscreen, mouse, or trackpad — and would be equally at home on both iOS and macOS.