Combine Rows only keeping unique values

Hi memote1, check this:

Output

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("hY/RDcMgDERXifiOdLbBBmaJsv8ahcRtI0pSCUuH79kc2xa4aDtkYQ0CBtdcmly8IuToadjXxpqVxlY3FSIQ4vQZmEC9DGJv8KsHOCNyN0Y93cyMOIOvfR8i1RLtkmaZeMlT2QOTwXLLFKra36czDP1cZnRE+rfwEZFMd/9yL4FzT2CDdnZ/AQ==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [PARTICIPANT_ID = _t, DOSE_ADMIN_DATE = _t, RCV_ELSEWHERE_1ST_DOSE = _t, RCV_ELSEWHERE_2ND_DOSE = _t, RCV_ELSEWHERE_MEASLES_DOSE = _t]),
    ChangedType = Table.TransformColumnTypes(Source,{{"PARTICIPANT_ID", Int64.Type}, {"DOSE_ADMIN_DATE", type date}, {"RCV_ELSEWHERE_1ST_DOSE", type date}, {"RCV_ELSEWHERE_2ND_DOSE", type date}, {"RCV_ELSEWHERE_MEASLES_DOSE", type date}}, "en-US"),
    GroupedRows = Table.Group(ChangedType, {"PARTICIPANT_ID"}, {{"T", each {[PARTICIPANT_ID]{0}} & List.Sort(List.Distinct(List.RemoveNulls(List.Combine(List.Skip(Table.ToColumns(_)))))), type table}}),
    Transformed = Table.FromList(GroupedRows[T], (x)=> x, Value.Type(Table.FirstN(ChangedType, 0)))
in
    Transformed