Sort:  

Is it Hive Keychain API compatible or a separate tool that needs new implementation in all dapps?

@muwave the dev for @peak.open created an SDK that makes all wallets available with it and another developer did an SDK as well that enables them. So from what i understand new projects should use one of the SDKs when implementing wallets. But retrofitting is a different story.

So the short answer is no ;)

Also @asgarth or @yozen can give a some insights as they've both integrated peak vault into different apps.