If you have an older TV that is nor a smart TV or if you simply want to add an Android box to your existing TV, an external TV Box is the answer.
There are many models out there and many operating systems. One of the best and most mature OS for a TV box is Android. This is because it has many applications and can do much more then operate a TV, for exemple, it can be used as a tablet with all the apps that are available to an Android tablet.
A TV box should have a strong processor with enough RAM and internal storage.
The Bqeel 4k Android TV Box model U1 Pro checks all the boxes:
CPU: RK3318 Quad-Core 64bit Cortex-A53
OS: Android 9.0
ROM: 64 GB
WIFI: 2.4GHz and 5GHz
USB interfaces: 1*USB 3.0; 1* USB 2.0