Combinations of Multiple Items using Power Query or DAX

This challenge is a good one. Below is M code that will meet it. You can modify the AddGroupSizes step to change the number of groupings that is currently set to 3 and 4.

let
    Source = Excel.CurrentWorkbook(){[Name="Data"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Grouping", type text}, {"Item", type text}, {"Order", Int64.Type}}),
    #"Grouped Rows" = Table.Group(#"Changed Type", {"Grouping"}, {{"DataGroupSize", each Table.RowCount(_), type number}, 
{"Data", each Table.AddIndexColumn(_,"Index",0,1), type table}}),
    AddGroupSizes = Table.AddColumn(#"Grouped Rows", "GroupSizes",each  {3,4}),
    #"Expanded GroupSizes1" = Table.ExpandListColumn(AddGroupSizes, "GroupSizes"),
    AddActualGroupSize = Table.AddColumn(#"Expanded GroupSizes1", "GroupSize", each if [DataGroupSize] < [GroupSizes] then [DataGroupSize] else [GroupSizes]),
    #"Expanded Data" = Table.ExpandTableColumn(AddActualGroupSize, "Data", {"Index"}, {"Index"}),
    #"Filtered Rows" = Table.SelectRows(#"Expanded Data", each ([Index] <= [GroupSize])),
    #"Merged Queries" = Table.NestedJoin(#"Filtered Rows",{"Grouping"},#"Changed Type",{"Grouping"},"Data",JoinKind.Inner),
    AddItems = Table.AddColumn(#"Merged Queries", "Items", each List.Range([Data][Item],[Index], [GroupSize])),
    #"Filtered Rows1" = Table.SelectRows(AddItems, each List.Count([Items]) = [GroupSize] ),
    Transform = Table.TransformColumns(#"Filtered Rows1",{{"Items", each Text.Combine(_,","), type text}}),
    #"Removed Other Columns" = Table.SelectColumns(Transform,{"Grouping", "GroupSizes", "Items"})
in
    #"Removed Other Columns"