How to find Min and Max Dates across multiple Columns in Power Query

How to find Minimum and Maximum Dates across multiple Columns in Power Query
Scenario:

Suppose, we have the multiple Date Columns like [Act Date1], [Plan Date1], [Act Date2] and [Plan Date2] as follows.

Now we want to find the Min and Max Dates across the 4 Columns and rows as well. We can achieve this Scenario using the following Power Query:
1) Min and Max Dates across the Columns of 4 Columns :

let

    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("VZHJDYAwDAR74Y1EvLmgFpT+2wABweOfHzNarfc8F9ts35SkZb1vdb8NZ3rvsT7CAYEyBKOgBAhyhqAgIDtDLhByEJCdIVcIJQh/tli0ga+BL84ji+9qga/Ooya+ZT3wzXm0xLPmTB/fnWdJPGvO9Am7C2yJ8gor+1AKNdF+zjTGBQ==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"Act Date1" = _t, #"Plan Date1" = _t, #"Act Date2" = _t, #"Plan Date2" = _t]),

ChangeType = Table.TransformColumnTypes(Source,{{"Act Date1", type date}, {"Plan Date1", type date}, {"Act Date2", type date}, {"Plan Date2", type date}}),

MinOfCols = 

Table.AddColumn(ChangeType, "MinDate_Cols", each List.Min(ChangeType[Act Date1] & ChangeType[Plan Date1] & ChangeType[Act Date2] & ChangeType[Plan Date2] )),

MaxOfCols = 

Table.AddColumn(MinOfCols, "MaxDate_Cols", each List.Max(MinOfCols[Act Date1] & MinOfCols[Plan Date1] & MinOfCols[Act Date2] & MinOfCols[Plan Date2]))

in

    MaxOfCols

Result:

2) Min and Max Dates across the Rows of 4 Columns :

let

    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("VZHJDYAwDAR74Y1EvLmgFpT+2wABweOfHzNarfc8F9ts35SkZb1vdb8NZ3rvsT7CAYEyBKOgBAhyhqAgIDtDLhByEJCdIVcIJQh/tli0ga+BL84ji+9qga/Ooya+ZT3wzXm0xLPmTB/fnWdJPGvO9Am7C2yJ8gor+1AKNdF+zjTGBQ==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"Act Date1" = _t, #"Plan Date1" = _t, #"Act Date2" = _t, #"Plan Date2" = _t]),

ChangeType = Table.TransformColumnTypes(Source,{{"Act Date1", type date}, {"Plan Date1", type date}, {"Act Date2", type date}, {"Plan Date2", type date}}),

MinOfRows = Table.AddColumn(ChangeType, "MinDate_Rows", each List.Min({[Act Date1], [Plan Date1], [Act Date2], [Plan Date2]})),

MaxOfRows = Table.AddColumn(MinOfRows, "MaxDate_Rows", each List.Max({[Act Date1], [Plan Date1], [Act Date2], [Plan Date2]}))

in

    MaxOfRows

Result:

Thanks, TAMATAM