If you need Netflix and Viu, official Google certified Android TV OS device like Mi Box S and Nvidia Shield TV are the best choice along with Google Chromecast dongles.
As for your iptv please check your provider. Most of them should support Mi Box S unless they do not support Android 8.
Mi Box S has Netflix 4K support and built-in support of Chromecast 4K function. It also costs less than Chromecast Ultra.
The official supported way to watch Viu on TV is through Chromecast for Android device or Apple TV Airplay for iOS device.
https://www.viu.com/ott/sg/en-us/copyright-statement/tips
4. Can I watch the shows on TV?
Yes, only Viu Premium members would be able to enjoy their favourite Asian entertainment in full HD on their TV.
However, do note that TV rights are only applicable for selected shows on:
- Selected Samsung Smart TV or;
- Casting via Google Chromecast for Android devices & via AirPlay on Apple TV for iOS devices only. Laptop/PC to TV is not supported.