Given the common architecture, I wonder if this'll available in the future. It would be convenient for groups who benefit from the walled garden, namely children and senior citizens, to run iPadOS on a Mac.
Well, first, you can lock down a Mac so it will only run Apps from the (Mac) App Store. You can create users without admin access, set parental controls etc. to get a similar "walled garden" effect.
Second, you can now install and run selected iPad/iPhone Apps on M1 Macs - it is up to the developers to decide whether they offer their apps in this way.
Problem is, iPads/iPhones have different screen sizes, shapes, you tend to hold them closer than Macs, touch screens have different design affordances c.f. mouse/trackpad/keyboard based systems... so software designed for iPad tends to work better on an iPad than a Mac, and vice-versa. That's discounting Apps that use the accelerometer, compass, camera etc. So far, people haven't been raving about the new facility to run iPad apps on a Mac...
Or, you could... buy an iPad? They're cheaper than Macs....
Or, Apple might do a U-turn and produce a convertible 2-in-1 iPad/Mac combo with a touch screen to compete with PC 2-in-1s. Currently, the gospel according to Appledom is that touch screens on laptops suck, and so shall it remain until Apple make a touchscreen laptop, from which point on they will be the best thing since unsliced bread...