Are there microtransactions in this game?

Yes there are but only to make your life a lot easier as early as possible. You can purchase locked outfits, vehicles, and weapons you don’t have access yet using Prestige Points. You can buy Prestige Points using real money. Prestige points can also be used to purchase additional Perk Points and get bundles of crafting resources.

Fortunately, there are no Prestige-exclusive weapons, apparel, or vehicle; you can get them eventually through normal game progression - by upgrading your homebase and your facilities. Clothing items need to be farmed by liberating Outposts. Prestige Points will just allow you to get a weapon, apparel, or vehicle earlier than necessary, without the hassle of farming for the needed materials.

You can also pick up Prestige Points from Treasure Hunt locations though their amount is miniscule and limited. (You can get around 450 prestige points from all Treasure Hunt locations.