custom formula in Query mode that lists all distinct values for a certain variable (see example)

Take a look at this M code, since you said "Query"

It generates this table

I did it in multiple steps so you could see how each worked.

1) In Power Query, select New Source, then Blank Query
2) On the Home ribbon, select "Advanced Editor" button
3) Remove everything you see, then paste the M code I've given you in that box.
4) Press Done

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WcnRyVtJRCknNSc1NLMpOLcnMS1eK1YGJ++flZOalKjimgMWcnFyAYuGpSQpIXOf8vLTUotS85FSl2FgA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [#"Account ID" = _t, Programs = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Account ID", type text}, {"Programs", type text}}),
    #"Grouped Rows" = Table.Group(#"Changed Type", {"Account ID"}, {{"All Rows", each _, type table [Account ID=text, Programs=text]}}),
    #"Added Custom" = Table.AddColumn(#"Grouped Rows", "Programs Column", each Table.SelectColumns([All Rows], "Programs")),
    #"Added Custom1" = Table.AddColumn(#"Added Custom", "Custom", each Table.ToList([Programs Column])),
    #"Extracted Values" = Table.TransformColumns(#"Added Custom1", {"Custom", each Text.Combine(List.Transform(_, Text.From), ","), type text}),
    #"Expanded All Rows" = Table.ExpandTableColumn(#"Extracted Values", "All Rows", {"Programs"}, {"Programs"}),
    #"Removed Other Columns" = Table.SelectColumns(#"Expanded All Rows",{"Account ID", "Programs", "Custom"})
in
    #"Removed Other Columns"