Hello there newbie! 👋 I think you don't have to pay anything to start publishing your game. We published ours smoothly on itch.io, but it's not the same for App Store and Play Store. You can follow the trending games, follow fellow game developers, artists, and music composers. You can also write your dev logs to show your game's work before release, this will help you build your own community a bit. If you're looking for assets, this is the place.
Wish you luck for your upcoming game! ☺️