I have Roku boxes on my smart TVs. I found that the TV apps will sometimes lag and buffer while the same apps through the Roku do not.
Plus, if you buy the Roku 4k+ unit (about $39.95 at Walmart) you can program Roku's very simple remote to turn on and off your TV and control the volume.
And if you lose the remote, replacements are dirt cheap from Amazon. I've got Roku remotes all over the house!
My TV remote talks to the cable box and bluray. If my Roku was plugged in it would probably to that too. What’s creepy is I didn’t even set anything up. The TV just handles it. I don’t like my toys talking to each other like that, what if they decide they don’t like me.