There are many ways to discover Android and Roku apps. For Fire TV, I keep my eye on
AFTVNews,
newly released apps, and the
free app of the day. I like to read the reviews before making a purchase. I think all of this would be very frustrating without a keyboard.
The Roku is worse because a lot of good apps never make their channel store.
I just happen to have set up a streamer at my sister's house. She has only an iPad. Just tapping out all the words was unpleasant.