I have a friend who recently dumped Comcast cable for YouTube TV and I set her up with the little
Onn Android TV 4K streaming box from Walmart. It's a very competent little streamer and unbelievably only costs $20! And it has surprisingly gotten several software updates since it came out earlier this year. Had some bugs to start but they've gotten those squashed. Just gained an HDR auto feature, so that it will switch between SDR and HDR automatically based on whatever video you're playing. When I tried it out earlier this year, it felt pretty snappy and I read that a new update just made navigating the Android TV home screen UI/menus even faster.
One reason I like it for YTTV viewers is that Android TV is from Google and the built-in Google Assistant voice interaction works well with YTTV. Also, the remote for the Onn device has a dedicated TV button which, when pressed, launches YTTV. (It'll launch on the home screen of that app or, if the app is already running, will just take you back to whichever live channel was running when you were last watching YTTV.) There's also a channel up/down button on the Onn remote for channel surfing. And there are four shortcut buttons at the bottom of the remote for quick-launching YouTube, Netflix, Disney+ and HBO Max.
It does support AC wifi with MIMO but no ethernet. Also, only the basic HDR10, not Dolby Vision or HDR10+. It supports Dolby audio but not Atmos. Runs all the major apps, including Apple TV.
It has pretty much the same internal hardware as the Google Chromecast with Google TV, which costs $50 (or $40 on sale right now). I've used both devices and definitely prefer the Onn remote control (which was actually designed by Google too). The home screen UI of Google TV vs. the Onn's regular Android TV isn't that much different, especially now that Android TV supports the Google TV universal watchlist feature.