Is there an interactive config cli command? i.e. prompt for all require and requireSecret values?

There is not currently - and more fundamentally there is no way to know all the config that a program might read except by running it. We are expecting to do a large overhaul of the config system in the near future to help address this (and a number of other related limitations of the current mode) - https://github.com/pulumi/pulumi/issues/1052 is tracking on key aspect of that.