[ben_w]

Even if it's a monopoly (not strictly required), nationalisation means the nation becomes the only shareholder, and the profits are directed to the growth of the nation rather than the business.

Apps are probably not the right target for that, but Amazon might well be — it has expanded to the point it needs its own delivery network because government owned post isn't enough in certain countries.

It would be a massive pain to do this well, certainly more than would fit into a comment box like this. And not just because it's a multinational, and different governments will have different opinions about the process of nationalisation.