https://www.gamespot.com/articles/pubg-dev-confirms-more-loot-boxes-says-it-wasnt-pr/1100-6455398/

PUBG currently allows players to spend extra money on loot boxes that contain cosmetic items. More microtransaction options are coming to PUBG in time, but they will never contain items that affect gameplay, according to Bluehole CEO Changhan Kim and lead designer Junhyuk Choi. During a Q&A at the G-Star event recently, the pair confirmed, "We will never add anything [through loot boxes] that affects the gameplay."

According to a translation posted by Bluehole, they also acknowledged that PUBG is seeing "relatively strong demand" for cosmetic items. You can expect Bluehole to add more over time, but not until after the 1.0 release later this month. It remains to be seen what these cosmetic items will be; some of the existing ones include outfits and other player-customization options.