Don't use a tablet or a compact screen if you are wanting to actually play games.
Monitors have been used for decades.
Small compact portable tablets or tablet-likes as a monitor are a compromise: quality for portability.
A tablet/tablet-like as a monitor is an accessory, as opposed to an actual peripheral.
You will regret not getting an actual monitor.
Any regrets you have with an actual monitor can be placated by slaying in vidya

Edit:

If you are unsure, buy a cheapish monitor on Amazon or wherever. You can get a 1080p60 monitor for like $100.
Whilst it is somewhat an investment, it will last you a few years, and you will find out what you want from a monitor while still being able to play games etc.