Trying to activate NFL app, the only prompt is for TV provider, no option to select Roku. Tried multiple ways without success. Any advice appreciated.
Roku isn't a provider. There's a lot of channels/apps that require a cable TV provider with a package that contains that channel. You can subscribe directly to NFL+ and then sign in using the NFL channel/app on your Roku device, but I don't really know what that gives you. Some of the cable-like streaming services like Fubu, Philo, Sling, etc. have a package that includes the NFL channel. A few months old, but...
https://www.roku.com/blog/how-to-stream-nfl-games-on-roku-players-and-roku-tvs