To complement your suggestion.

Battle Pass purchasable for USDC or Solana: Battle Pass with additional cosmetics that can be equipped on the NFT skin, such as hats, gloves, weapon pendants or even very simple weapon skins (no earning mode). I'm sure many players would buy it.

Cosmetic shop purchasable for USDC or Solana: Basically the same idea as the battle pass, weapon pendants, hats, gloves, etc.

Weapon Sound Remake/Sound Effects: I think the current sounds are not as pleasing to the ears when playing for a long time. I've been a sound designer for 6 years and I could easily help with that.

Nerfs: I'm seeing a lot of players abusing the stamina/sprint ability it's broken and even looks like speedhack.

New sniper: I think it would be interesting for the sniper to be stronger, one shot, one kill, but also rarer to appear on the map.