You don't need a Roku to watch Roku's free movies

Roku is also corralling notable free content across its ecosystem into a new section, Featured Free, which will show up in the navigation menus of its devices. It features movies and TVs from networks like ABC and the CW, as well as more obscure sources like Tubi. You won’t actually watch anything in that section though, instead it’ll redirect you to the appropriate app to get things started (and install it if necessary). Featured Free will roll out across Roku devices over the next few weeks.