Buying apps on appstore for ipad while using Mac

Is there some (*strange*) reason that Apple does not allow you to buy an app for your ipad while on the mac? Procreate, one of the most popular apps simply does not have a button to buy on the app store web site. Then if you go to the app store app (on the mac) you do not find Procreate at all! You find a bunch of tools for procreate, etc. but not the actual program. What I want to do is get it for a friend. Is that not a thing? Don't people gift other people apps? If not why not? If yes, what am I not seeing here? This seems to happen to me every time I use the app store. I can never figure out why people like Apple so much when they seem to make it difficult to use their products at every turn.