Not Like function

You can do this in a single step with a custom column.

Text.Combine(List.Intersect({Record.ToList(_), Pets[Pets]}), "|")

Full sample query you paste into the Advanced Editor:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WKslIVVBITixRKE4sUdJRcslPB5K5lQoZ+aXFqUqxOtFQofyy1CKFxLwUBRADyHcGKkfIOoM1+1YqpCcWpaTmgWU88ouAJsDkXPKB6mMB", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t, Column3 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Column1", type text}, {"Column2", type text}, {"Column3", type text}}),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "Result", each Text.Combine(List.Intersect({Record.ToList(_), Pets[Pets]}), "|"), type text)
in
    #"Added Custom"