I don't know if this is possible, from a design conventions point of view, but it would be nice, that in case of selecting "Json parsed object" to be able to specify a sub-level for retrieval.
I'll explain: Most of the consumer and PV devices I work with publish their payloads as: {value: 240.5}, for example.
If one could tell the node to get the value property of the payload, it would simplify the flow, saving a repeating change node.