PUBG was the 'game of 2018' and its popularity will only grow in 2019. The popularity of the game is owing to the fact that it is free on mobile and is not restricted to the high-end devices. The game developer, PUBG Corporation, has made the game more accessible by making sure that the people with affordable devices can also experience its unique challenges and compete with other gamers without any hiccup.
If you use an Android 5.1.1 and above and minimum 2 GB of RAM, you can still play the PUBG game, tho it may not "high" graphics in your settings but still you can enjoy playing it with your friends. And also, I think having a high graphics is not considered to be a pro player if you are good in shooting or killing players and you have strategy, you may considered you a pro player.