So people with Android where sideloading has been a normal thing for many years have been dangerous? Could they harm other people by creating their own app and

So people with Android where sideloading has been a normal thing for many years have been dangerous? Could they harm other people by creating their own app and installing it on their Android without paying anyone a yearly subscription? It used to be normal in the past that people would OWN a computer and they would run ANY software on it. Why should we allow a greedy company like Apple to change that? Both android and ios implement sandboxes and apps can't gain complete access over the device in most cases so I don't see any security benefit.