I'm wondering if I can buy a game for example PUBG on a newly created acc/account that's still level 1?
Yes, even level 0 accounts can purchase games.
Technically you can buy a Steam game without an account, provided that you buy it in a physical store. That's how I was first introduced to Steam. Of course you have to create an account to activate the Key that comes with the games, but physical games, like their digital counterparts, have no level requirement.