Yes, on a technical level you can use an OLED TV as a computer monitor. However, it is typically not recommended to use an OLED TV. This is due to a number of reasons.
The first reason is the refresh rate. The refresh rate of a TV is typically lower than that of a monitor. Even though OLED TVs have a good refresh rate, it is still likely lower than a monitor. Therefore, it is unlikely going to be the best option.
If you want to use an OLED TV as a computer monitor, you will also need to take into consideration the size of the screen. If you are looking to use a large TV, this is not the best option as the resolution of the image displayed will not be fantastic.
However, if the OLED TV screen is smaller, it can be a great alternative to a monitor.