The existing \conninfo command gets its values from libpq APIs. You are
changing all of this to make a server query, which is a totally
different thing. If we wanted to take a change like this, I don't think
it should be reusing the \conninfo command.
But I don't really see the point of this. The information you are
querying is already available in various system views. This proposal is
just a shorthand for a collection of various random things some people
like to see. Like, by what reason is application name included as
connection info? Why not any other session settings? What about
long-term maintenance: By what logic should things be added to this?