change column type programmatically

OK, that clarifies a bit: so the columns you specify in Table1 are columns that are included in Table2.

Apart from the challenge to change your Table1 to a list with lists, another challenge is to convert text like "type number" from a text to an actual type.

So, it's rather complicated, but the good news is that the following codes accomplishe the tasks. The "TextToType" step converts your textual types to actual types.

Query ColumnSpecs in which the Source step represents your Table1:

let
    Source = #table(type table[col name = text, col type = text],{   {"Sales", "type number"}, {"Profit", "type number"}  }),
    TextToType = Table.TransformColumns(Source,{{"col type", Expression.Evaluate}}),
    FieldValues = Table.AddColumn(TextToType, "Custom", each Record.FieldValues(_)),
    RemovedColumns = Table.RemoveColumns(FieldValues,{"col name", "col type"}),
    TableToList = RemovedColumns[Custom]
in
    TableToList

And Table2:

let
    Source = #table({"Sales","Profit"},{{1000,300},{100,40}}),
    #"Changed Type" = Table.TransformColumnTypes(Source,ColumnSpecs)
in
    #"Changed Type"