I agree with you that it is technically better to keep the media player and screen separate, since media players usually require more frequent updates. In addition, the support given to Smart aspects of a TV is not great. I wish all TV’s were simply screens, but unfortunately it is hard to find a TV that isn’t smart! I recently purchased a Sony TV which has Android TV as its smart component. Not bad actually and quite adequate for many/most users. Not as nice as a Shield TV player, nor the Apple TV 4(K), but the Sony is very useable in Smart mode. Choosing Android TV was a good choice in my opinion. It will be supported. I assume TV’s with a Roku, or even a Fire TV, base will also be well supposed. My older ( not that old) LG had terrible smart TV support.
The one caveat in all of this is that you have to be careful when it comes to support for Canada. The Apple TV is pretty darned good but Android TV seems to be lagging for some reason. The rest are probably more of a pain than anything unless you go the vpn, etc... route.