Not sure if I would call it marketing, but ..
The concept of making it an early action ... Get account information and suggest keychain is a great idea.
I was just literally mentioning to my husband how ADAs wallet is a pain in the ass and they should make a "Keychain" type wallet for ADA.
Posted Using LeoFinance Beta
Marketing for Keychain is marketing Hive. Like a payment app ( Paypal and so on)
That's the most neutral way for hive marketing, and it could be paid with recommended dapp inside ( for example splinterlands, peaked and so on).
Hive alone with keys is the very unlikely average user will use many different dapps. With keychain it is unlikely only use one :)
Also marketing could paid by DAO because its 100% neutral and the "recommended" area could be paid to DAO fund for example :)