Nearest match from TABLE1 to Table2

Hi Topaz_Installer,

You can copy this into a new blank query

let
    Tbl1 = Table.TransformColumnTypes(Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjSwMgAhpVgdOMcUiWOILGMIlIkFAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Table1 = _t]),{{"Table1", type time}}),
    Tbl2 = Table.TransformColumnTypes(Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjSwMgAhpVgdOMcQmWOGxDFEVmYIlIkFAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Table2 = _t]),{{"Table2", type time}}),
    AddCustom = Table.AddColumn(Tbl1, "Approx Match", each List.First( Table.SelectRows( Tbl2, (x)=> x[Table2] >= [Table1])[Table2] ), type time)
in
    AddCustom

Give this a go for an approx match

Table.AddColumn( Tbl1, "Approx Match", each List.First( Table.SelectRows( Tbl2, (x)=> x[Table2] >= [Table1])[Table2] ), type time)

with this result

Ps. If this helps solve your query please mark this post as Solution, thanks!

let
    Table2 = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjSwMgAhpVgdOMcMiWOILGMIlIkFAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Timestamp = _t]),
    #"Changed Type Table2" = Table.TransformColumnTypes(Table2,{{"Timestamp", type time}}),
    Table1 = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjSwMgAhpVgdOMcUiWOILGMIlIkFAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Timestamp = _t]),
    #"Changed Type Table1" = Table.TransformColumnTypes(Table1,{{"Timestamp", type time}}),

    #"Added Match" =
        let l = #"Changed Type Table2"[Timestamp]
        in Table.AddColumn(
            #"Changed Type Table1",
            "Match",
            each let dev = List.Transform(l, (ts) => Number.Abs(Number.From(ts - [Timestamp]))), pos = List.PositionOf(dev, List.Min(dev))
                in l{pos}
        )
in
    #"Added Match"

A showcase of powerful Excel worksheet formulas,

=INDEX(Table2[Timestamp];LET(dev;ABS(Table2[Timestamp]-[@Timestamp]);MATCH(MIN(dev);dev;)))