I just recommended my parents the Sony X900E, hearing it had Android on it, thinking it could do whatever any other Android could do. I was surprised to learn that Android TV is actually quite limited, and doesn't even come with a web browser.
I followed some guides to manage to force it to install the Chrome browser from a PC, and it worked, and I got chrome running. But I still can't get it to play any video site. It's almost like the TV itself is redirecting my DNS requests - sites like www.sportshd.com get redirected to some other weird ww8 site, which does not happen to any other PC or device on this same wifi network. Sites like Rogers Anyplace TV just say "unsupported browser", even though it's Google Chrome. Sites like 123movies or Gomovies just never load.
Is there a way to get the web browsing experience on the Android TV, the same as it is on any other Android? I've got a mouse and keyboard, I just want a web browser that is actually capable of loading these websites.
I'm sorry to break it to you, but trying to use a browser on Android TV is a mistake. You're not meant to do so, and trying to do so will only result in frustration. I'm not sure why you thought this would be a good idea, but there you are.
So here's some ideas:
The big reason why you won't find a browser on Android TV is that browsers and 10-foot UIs don't work . A browser is meant to have lots of little details and require fine grained control. A TV is meant to have large details and course-grained control. Yes, you can make it work, but you're 1 in 10 million; it's not a use case that Google considers important, and I agree with them. Connecting a mouse to an Android TV is almost completely unheard of. Maybe someday Google will support a browser on Android TV, but I don't think it'll ever happen and if it did, I'd never use it.
Android TV supports Chromecast. The device you cast from is not serving the content to the TV. It's sending the TV a URL or something similar, then the TV downloads the stream. You'd only need a Chromecast device if you wanted to plug into a legacy TV. You might be able to get most of your websites to work by casting from your phone.
Most of us a pretty happy with our Android TV devices. I use and only use Android TV apps - Netflix, Hulu, HBO Now, etc, and they all work just perfectly. I'm not trying to use a TV for a web browser because I know that it's not fit for that purpose.
In the future, I'd recommend that you do a little more research before you buy something that you have no experience with.