You can use universal IPTV players like IPTV Smarters Pro. It has versions available for Android TV as well.
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My experience with this player is good and bad. The old version that exists for smart tv works very well, but the new version with a lot of options is completely unusable on Android tv. It is possible that it is the TV (although I doubt it), but I am sure that it is not a question of the list or the speed of the internet, considering that there are players that work perfectly on the same TV with the same list.