Helldivers 2 is currently #1 on the Steam top sellers list for paid games in the US. It's ahead of Palworld. It's also the #1 most pre-ordered game on the PlayStation Store in the US and other regions
You can earn the premium currency in-game but the rate is quite slow. Purchasing a 1000 Super Credit item is likely to take between 25-100 hours, and is equivalent to $10.