Yes, for sure, gamblers can use POLi to play slots. You might have even played slots with your POLi unknowingly. Top game providers in the online gambling industry provide slots. Slots usually come with the best RTPs, and gamblers might as well hit the jackpot playing them.
However, gamblers should remember that you can only use POLi to deposit, and you will withdraw your POLi slots earnings into your local bank account, or other withdrawal means supported by the bet sites.