Mechanism to customize rendering of state/props data types

When using React from transpiled languages, the way KeyValue.js renders state/props entries is pretty unusable for non-primitive types (int/string). I was hoping dev-tools could check for existence of a function on Props/State (or some other mechanism, maybe toStringTag) that would allow app developer to provide a custom display for each entry in the Props/State. If you provide a custom formatter, you give up the ability to edit those fields.