Agreed. It sounds like you're having the same experience as me, as a newcomer to Roku.
Hunting the reference documentation (or Googling) for examples of what should be the most basic functionality requirements for a TV app is 'exhausting' to say the least.
It's taken me days to just get a RowList to display content from a simple JSON feed containing categories and items within them. Even that came from an old random Github repo. And I still have absolutely no clue how to play the videos the items point to. 😬
Like you, I also need to simply need to have a "Watch Now" button at the top of the screen to play a live HLS stream.