There is certainly something to be said about being able to answer questions about another system by poking at it, but that is a scripting task. You would be better served by a scripting language. And, as it happens, most scripting languages come with REPLs. That is a solved problem that was solved long before Go was ever imagined.

Just because you are building a particular systems program does not mean everything you do has to be a systems problem. And, really, if you don't exactly know what you're building, it is probably too soon to consider any of it a systems problem.