Merged Query Question

Different Approach:

let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    Table1 = Table.TransformColumnTypes(Source,{{"Project", type text}, {"Item", type text}, {"Cost", Int64.Type}}),
    Source2 = Excel.CurrentWorkbook(){[Name="Table2"]}[Content],
    Table2 = Table.TransformColumnTypes(Source2,{{"Project", type text}, {"Budget", Int64.Type}}),
    Merge = Table.NestedJoin(Table1,"Project",Table2,"Project","Merged"),
    #"Expanded Merged" = Table.ExpandTableColumn(Merge, "Merged", {"Budget"}, {"Budget"}),
    #"Grouped Rows" = Table.Group(#"Expanded Merged", {"Project"}, {
        {"all", (t)=>Table.FromColumns(
                    Table.ToColumns(Table.RemoveColumns(t,"Budget"))
                    & {{t[Budget]{0}} & List.Repeat({null}, Table.RowCount(t)-1)},
                    {"Project","Item","Cost","Budget"}), 
        
        type table [Project=nullable text, Item=nullable text, Cost=nullable number, Budget=nullable number]}}),
    #"Expanded all" = Table.ExpandTableColumn(#"Grouped Rows", "all", {"Item", "Cost", "Budget"})
in
    #"Expanded all"