Special concatenation

[snb]

I do not understand why you use 'Let'. The use of it has become redundant for more than 20 years.

To 'walk' in your approach:

Sub M_snb()
   sn = Sheet1.Cells(1).CurrentRegion
   
   For j = 2 To UBound(sn)
     For jj = 1 To UBound(sn, 2)
       c00 = c00 & IIf(jj = 1, sn(j, jj) & ";", """" & IIf(jj = 4, Format(sn(j, jj), "0.00"), sn(j, jj)) & """;")
     Next
     c00 = c00 & vbLf
   Next
   
   MsgBox Replace(c00, ";" & vbLf, vbLf)
End Sub

or

Sub M_snb_002()
   sn = Sheet1.Cells(1).CurrentRegion
   
   For j = 2 To UBound(sn)
    c00 = c00 & """" & vbLf & Replace(Join(Application.Index(sn, j), """;"""), """", "", , 1)
   Next
   
   MsgBox Replace(Mid(c00, 3), """0""", """0,00""")
End Sub