I brought iPad 11” last year during my family travel. I use it for work (checking emails, review office docs and Ms Team), take family selfie pictures (I use Magic Keyboard), reading while waiting for plane or train, listening music & watch Netflix (so I don’t have to drain my iPhone battery) plus I feel safer because I can charge my iPhone using iPad (no need to bring power-bank separately).
Having said that, I would say, iPad can do things more comfortably compared to iPhone or Mac. It’s not mandatory device but it can be very useful especially when traveling. Also, it looks like the build quality of magic keyboard (mine is still the old one) is better than macbook air which made it more suitable for mobile usages.
1. When you add a Magic Keyboard, the thickness and weight is not much difference between bring in a 12 inch MacBook or 13 inch MacBook Air.
2. Waiting for plan or train, listen to music etc is better suited with phone usage. Watching Netflix on bigger screen on Mac is much better experience.
3. Since you are going to use the Magic Keyboard anyway, then doing office work, checking emails and MS teams is much more efficient on MacOS. I don't need to juggling between different apps nor I don't need to use awkward stage manager to managing multiple different apps.
4. MacBook Pro has much larger battery than your iPad, doesn't it make more sense to charge your iPhone with MacBok instead of iPad?