おそらく前回の続きですね。
let
Src = Excel.CurrentWorkbook(){[Name="テーブル1"]}[Content],
Dst = Table.Distinct(Src, {"会社"}),
Src2 = Excel.CurrentWorkbook(){[Name="テーブル3"]}[Content],
Idx = Table.AddIndexColumn(Src2, "Index", 1, 1, Int64.Type),
Grp = Table.Group(Src, {"商品", "会社"}, {{"売上合計", each List.Sum([売上金額]), type nullable number}}),
Mrg = Table.NestedJoin(Idx, {"会社リスト"},Dst, {"会社"}, "NewC", JoinKind.RightOuter),
Ctm = Table.AddColumn(Mrg, "商品", each List.Distinct(Grp[商品])),
Exp = Table.ExpandListColumn(Ctm, "商品"),
Mrg2 = Table.NestedJoin(Exp, {"会社リスト","商品"}, Grp, {"会社","商品"}, "Idx", JoinKind.LeftOuter),
Exp2 = Table.ExpandTableColumn(Mrg2, "Idx", {"売上合計"}, {"売上合計"}),
Srt = Table.Sort(Exp2,{{"Index", Order.Ascending}, {"商品", Order.Ascending}}),
Del = Table.SelectColumns(Srt,{"会社リスト", "商品", "売上合計"}),
Ren = Table.RenameColumns(Del,{{"会社リスト", "会社"}})
in
Ren
でどうでしょうか。