Yes you can watch NFL+ on Roku and other streaming devices.
Roku streaming media player is the most popular streamer on the market. To watch NFL Plus, just download the NFL app. There is no standalone NFL+ app. Once you launch NFL streaming app on Roku, make sure you are signed in and have a NFL+ subscription. Then navigate to games to watch game replays or NFL+ tab to watch other exclusive content. It’s a bit confusing because you technically don’t need a subscription to access the NFL app. But you will be prompted for a subscription to watch NFL+ content.
Read about NFL Plus review and which plan to subscribe to watch game replays.