cfireba

You could steal something from Goa kingdom nobles and handle the bandits there to increase your infamy

Warlords are essentially someone who is not strong enough to carve his own territory against Yonko and chose to fly under government flag instead of being under Yonko. If you're strong enough to beat an admiral you can become Yonko. There's no need for the government permission. You can just carve out your own territory in the new world without being under government.