I'm confused by your post.
Why is adding another device not an option? You can program up to 48 devices into an MX-880? But also why would you want to add another device? Not of that is clear, vs what we were talking about.

The MX-880 has a FAV button. Where you can add 6 apps to jump to on each page. Following Edmund's directions, you can add every app jump you want except for the Pluto TV.

Also - You do know that you can rearrange the apps on the Roku Home screen right? You can put all the apps you use in the order you want and delete apps you don't want or use.
You are making it sound like you have 50+ apps on your Roku scattered everywhere and takes forever to scroll to the ones you want. Something doesn't sound right.