Firstly I love now TV but I also love Netflix and amazon, streaming is the future so please can we get all are apps on one great device,at the moment it's PS4,Xbox or roku streaming stick the latter I am using at the moment but need better,thanks
you'll need to buy the more expensive roku box which gives you the freedom (if apps are available).
the nowtv box is a roku box locked for sky, who own nowtv, Netflix and Amazon are competitors. what you are asking for is similar to saying to tesco, i like asda and Sainsbury too, can you also have their stores within your stores... not going to happen.
if you want freedom, you'll need to purchase the roku branded box.