JSON column type in Power BI Dataflow

No. I am not aware of any way to return embedded lists, records, etc. in a loaded dataflow. 
This simple table:

let
  Source = #table(
            {"ID", "Name", "City"},
                {
                    {123, "Alice", {1.10}},
                    {456, "Bob", {100.150}}
                }
          )
in
  Source

has a nested list in the third column. When that is loaded in a dataflow nothing comes through into Power BI's Power Query. it is just a blank field.

You will need to do the expansion in the dataflow, or connect to the JSON directy from Power BI's Power Query if you want to expand it there.