The Alexa Voice Remote Pro for Fire TV devices is great, but one unfortunate decision made by Amazon is to not allow the customizable buttons on the remote to launch sideloaded apps. Thankfully, there is a workaround that uses my Remapper apps that will allow you to use either of the customizable buttons to launch any sideloaded app. Here is a full step-by-step guide for how to do it.

Guide

1. Go to the Remapper guide and select an app from the ones listed in Step 5 to be your sacrificial app. It needs to be an app that you plan to never actually use (i.e., you can’t choose Netflix if you actually have Netflix installed and want to keep using it). It needs to be an app that is available in your region (i.e., you can’t choose ABEMA if you’re in the U.S. because the app is not in the U.S. appstore). It should also be an app that isn’t one of the app buttons at the bottom of your Pro remote if you’re planning to also remap the app button itself.

   As an example for this guide, I am choosing the DirecTV app as my sacrificial app because my Pro remote app buttons are Prime Video, Netflix, Disney+, and Hulu and I never plan to use the real DirecTV app and the real DirecTV app is available in my area.

2. Search for and install the real version of your sacrificial app. So, as this guide’s example, I would be installing the real DirecTV app.
   
3. Assign a customizable button, either button “1” or “2”, to launch the real sacrificial app. The customizable button you assign here will be the one that eventually launches your sideloaded app. So, as this guide’s example, I would assign customizable button 1 to launch the real DirecTV app.
   
4. Test that the custom button correctly launches the real sacrificial app.
5. Uninstall the real sacrificial app. So, as this guide’s example, I would uninstall the real DirecTV app that I just installed in the previous step.
   
6. Follow the Remapper guide from start to finish to install the Remapper app that matches your sacrificial app. So, as this guide’s example, I would install the Remapper app for DirecTV. Be sure to not skip any steps in the Remapper guide!

   When step 11 in the Remapper guide has you press the app button on your remote, you should instead press the customizable button that you assigned in step 3 of this guide.

   When step 12 in the Remapper guide has you select the app you want to launch, you should select the sideloaded app that you want the customizable button to launch.
   

7. If you did everything correctly, pressing the customizable button on your Pro remote should now work to launch your sideload app. If you want to know more about how this all works, what you’ve just done is assign the customizable button to launch a non-sideloaded app but then replaced that non-sideloaded app with one that mimics it. The Remapper app, which is the one that mimics the non-sideloaded app, is just acting as a middle-man that launches the sideloaded app you chose whenever the customizable button launches the Remapper mimicking app.