There weren't any such thing when I started streaming in 2010, and my Roku was a set top box that worked really well with my existing TV.
I did try a Roku stick when they were introduced. If you wonder what that has to do with a Roku TV, you may remember (or just now be finding out) that the first Roku Sticks were MHL devices, not standard HDMI devices, and were initially sold as part of a "Roku Ready TV." I never had one of those, but when they came out with an HDMI version, I bought one.
I own a Roku Streambar, which is a third form factor Roku device. But in all this time I never owned a Roku TV.
I've used Roku TV devices. My sister had one at my mothers, and when my mother passed away, I had to handle a lot of things on site for a while and actually stayed there for a period of time. I used the Roku TV then, hated it, and attached a Roku Stick to it, making the fact it was a Roku TV no longer a factor. I used the attached Roku device, and just the screen and sound from the TV, not the Roku software and interface of the TV.
The reason is that the TV was very slow and sluggish. Well, at least compared to the higher end Roku devices I had attached to my TVs. I didn't like the infrared remote that came with the TV -- it was the infrared, line of sight part that I didn't like -- so I was going to get a Voice Remote anyway, so I just got a Stick for a few dollars more, since it included the Voice Remote anyway.
So while I never owned a Roku TV, I have used Roku TV, but wasn't impressed.
That could change. The owning part has actually changed.
I decided to add a third TV to the mix, putting TVs in the living room (existing) and two bedrooms (a TV was already in one bedroom). And, when I decided to make the purchase, the new Roku built TVs were on sale at Best Buy. So, I bought one.
I've installed it and used it a little. And I like it, so far. I'm going to try it for a bit and see if I continue to like it, or if my opinion will change.
My Streaming Life has never included a Roku TV of my own. Until now. I'll let you know how it goes.