Split current month values to daily

I am still curious what analysis/visual you plan to do, but this was a fun query challenge so I went ahead and did it (I think).  To see how it works, just create a blank query, go to Advanced Editor, and replace the text there with the M code below.

let
  Source = Table.FromRows(
    Json.Document(
      Binary.Decompress(
        Binary.FromText(
          "i45WclTSUTI1ABJGpkDCXN9Q38jAyADMNIayY3WilZyAIoYGIHFjvOpAxpmDVBiD5CwQyiwwjAOrMAERlghllvrGBqjKLExhlhoaINQB2XDzYgE=", 
          BinaryEncoding.Base64
        ), 
        Compression.Deflate
      )
    ), 
    let
      _t = ((type nullable text) meta [Serialized.Text = true])
    in
      type table[Product = _t, Qty = _t, Price = _t, #"Start Date" = _t, #"End Date" = _t]
  ),
  #"Changed Type" = Table.TransformColumnTypes(
    Source, 
    {
      {"Product", type text}, 
      {"Qty", Int64.Type}, 
      {"Price", Int64.Type}, 
      {"Start Date", type date}, 
      {"End Date", type date}
    }
  ),
  #"Added Custom" = Table.AddColumn(
    #"Changed Type", 
    "New Start Date", 
    each 
      let
        thisdate = Date.From(DateTime.LocalNow())
      in
          if Date.Month([Start Date]) = Date.Month(thisdate)
          then List.Dates(
            Date.AddDays(thisdate, - 1), 
            Duration.TotalDays(Date.EndOfMonth(thisdate) - thisdate) + 1, 
            #duration(1, 0, 0, 0)
          )
          else {[Start Date]}
  ),
  #"Added Custom1" = Table.AddColumn(
    #"Added Custom", 
    "New Qty", 
    each [Qty] / List.Count([New Start Date])
  ),
  #"Expanded DateList" = Table.ExpandListColumn(#"Added Custom1", "New Start Date"),
  #"Changed Type1" = Table.TransformColumnTypes(
    #"Expanded DateList", 
    {{"New Start Date", type date}, {"New Qty", type number}}
  )
in
  #"Changed Type1"

I didn't add the end date, but that should be straight forward if needed.  The above does what you were looking for expanding the current month to daily level and calculating the daily quantity.

If this works for you, please mark it as the solution.  Kudos are appreciated too.  Please let me know if not.

Regards,

Pat