To be clear, the OTT apps you use will primarily deliver audio in a compressed format so this isn't going to change with an external device such as Apple TV or a Shield. Amazon Prime maybe the exception. You will gain some video performance. Again, don't approach this as a means to find fault. If everything is working okay and to your satisfaction, leave it as it is. You've had the TV for a couple of weeks. Spend a few months, make a note of your Likes, Dislikes and then approach the problem step by step.
You need to remember that an upgrade here and there might eventually lead to something else along the chain that is more important to upgrade. This takes time to learn and understand.