Error #VALUE with long string in UDF in VBA for output in Excel

I use the below UDF to concatenate references to include the result in
an SQL query like ref in ('ref1', 'ref2', ...).

The UDF works just fine normally, but when I need to put a huge list of references,
I get #VALUE in Excel.

I already take a look at this answer, but I can't manage to make my UDF work...

I've tried to changed the type of the function from String to Variant (explicitly),
but it didn't change a thing...

I also tried ConcatSQL2 = A(0) and ConcatSQL2 = A for the output,
Dim A(0 To 0) As String for the declaration, ... and again it is not working...
I'm running out of ideas...

For info, the result string is expected to be about 220k long...
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Public Function ConcatSQL2(Plage As Range, Optional Doublon As Boolean = True)
Dim A() As String, _
    Cel As Range
ReDim A(0)

A(0) = "('"
For Each Cel In Plage.Cells
    If (Cel.Value <> "" And (InStr(1, A(0), Cel.Value) = 0 Or Doublon)) Then
        A(0) = A(0) & Cel.Value & "', '"
    End If
Next
A(0) = Left(A(0), Len(A(0)) - 3) & ")"

ConcatSQL2 = A(0)
End Function

Solution

Regarding @Rory's comments :

32767 is the maximum number of characters in a cell

I decided to write the output in a text file to be reused afterwards!

Here is the final solution

Public Function ConcatSQL2(Plage As Range, Optional Doublon As Boolean = True)
Dim A(0 To 0) As String, _
    myFile As String, _
    Cel As Range
'ReDim A(0)

A(0) = "('"
For Each Cel In Plage.Cells
    If (Cel.Value <> "" And (InStr(1, A(0), Cel.Value) = 0 Or Doublon)) Then
        A(0) = A(0) & Cel.Value & "', '"
    End If
Next
A(0) = Left(A(0), Len(A(0)) - 3) & ")"

myFile = "Path\FileName.txt"
Open myFile For Output As #1
Write #1, A(0)
Close #1

ConcatSQL2 = A
End Function