Keywords Text
cat The dog chased the cat.
dog The cat ate the bird.
bird The cat is a cat.
The dog, bird, and cat.
consumer watchdog
catwoman and bird
Dog and Bird


Code:
let
    Keywords = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    Text = Excel.CurrentWorkbook(){[Name="Table2"]}[Content],
    Index = Table.AddIndexColumn(Text, "Index", 1, 1),
    Split = Table.ExpandListColumn(Table.TransformColumns(Index, {{"Text", Splitter.SplitTextByAnyDelimiter({" ",",","."}, QuoteStyle.Csv), let itemType = (type nullable text) meta [Serialized.Text = true] in type {itemType}}}), "Text"),
    Join = Table.AddColumn(Split, "Custom", each Keywords),
    Expand = Table.ExpandTableColumn(Join, "Custom", {"Keywords"}, {"Keywords"}),
    IF = Table.AddColumn(Expand, "Custom", each if Text.Contains([Text], [Keywords]) then [Keywords] else null),
    Group = Table.Group(IF, {"Index"}, {{"Count", each _, type table}}),
    List = Table.AddColumn(Group, "List", each List.Distinct([Count][Custom])),
    Extract = Table.TransformColumns(List, {"List", each Text.Combine(List.Transform(_, Text.From), ", "), type text}),
    TSC = Table.SelectColumns(Extract,{"List"})
in
    TSC
Case sensitive and words contained keywords
List
dog, cat
cat, bird
cat
dog, bird, cat
dog
cat, bird

Code:
IF = Table.AddColumn(Expand, "Custom", each if Text.Contains([Text], [Keywords], Comparer.OrdinalIgnoreCase) then [Keywords] else null),
Case insenstive and words contained keywords
List
dog, cat
cat, bird
cat
dog, bird, cat
dog
cat, bird
dog, bird

Code:
IF = Table.AddColumn(Expand, "Custom", each if Text.Contains([Text], [Keywords], Comparer.OrdinalIgnoreCase) and Text.Length([Text]) = Text.Length([Keywords]) then [Keywords] else null),
Case insensitive without words contained keywords

List
dog, cat
cat, bird
cat
dog, bird, cat
bird
dog, bird

Code:
IF = Table.AddColumn(Expand, "Custom", each if Text.Contains([Text], [Keywords]) and Text.Length([Text]) = Text.Length([Keywords]) then [Keywords] else null),
Case sensitive without words contained keywords
List
dog, cat
cat, bird
cat
dog, bird, cat
bird