Not an expert, but it's a .txt file, that you can create and change the extension to .conf, used if I'm not wrong, to add/override? the default parameters of the wallet. It's located at /appdata/roming/(coin directory).  Commonly used to add nodes.

Not all the POS coins have .conf, usually the devs hardcoded the needed stuff in the wallet.

I think so the problem here could be that there are a very few wallets staking with a very few coins. Most of coins are in the way in/out of the ponzi address. Also, no movement in the blockchain means no coin maturing, so even the staking weight is more smaller. But I can be wrong.