Anyone could be an Aave protocol ecosystem developer, and there might be many type of incentives, anyone is capable of bringing governance proposal to fund further development on top of Aave protocol, as long as its approved over governance by AAVE holders anyone could bring a cool proposal/addition to the benefit of the protocol and get funds, you can find plenty of previous proposals hereand many more been discussed hereand sentiment voting here.

Even anyone with a good idea could just submit it to Aave protocol Grants DAO here.