You could use
https://github.com/belltown/Roku-NewVideoPlayer, which supports Roku videoplayer-style feeds, as well as RSS/MRSS/iTunes feeds.
It supports an unlimited number of category levels, the bottom two levels are displayed using an roPosterScreen with a filter banner by default. However, change 2 lines of code in UI.brs, as described in the header comments, and it will use an roGridScreen instead. It should work with your main videoplayer categories file, unless you've made any changes to the videoplayer code.
Feel free to use the code as an example, or even as the basis for your channel. Just don't expect any "support", especially if you aren't willing to do the work it takes to learn how to write your own code.