Get a USB dongle - you can probably use a generic one (I have one in my Xbox) but the Pi Hut has a few accessories which will be guaranteed to work. So pop this in and you should be able to use your old remotes.

However one thing you need to be aware of, is that most apps will throttle your resolution to 720p with a setup like that.

There is basically no way to get proper streaming from these apps except by buying a completely premade android device, and then never ever messing with it.

The DRM system they use for this is called Widevine.