I have a mostly positive opinion of this Android TV streaming device that has Chromecast built-in.
One thing I just realized, today, is that I can connect it to my phone's hotspot and cast to it from that same phone.
I seem to remember that, in most cases, the Chromecast and the casting device have to be connected to a common third device but, in this case, the phone is able to be the hotspot AND the casting device.
That makes for a very compact and simple setup.
While an Android TV device is very capable and the Chromecast capability might not seem very important, there are many times when I prefer to cast from my phone rather than install a particular app on the streaming device.