Counting Abandoned Flows

I used the group all rows to next the Pages, then used Table functions to filed it the Page has been visited Table.RowCount(Table.FindText([Events], "Projects Page"))

Note this just looks for the page rather than first and last pages. If you need that then the code would be a bit trickier

Data

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("vZjfb9owEMf/FStPrdSqubMvP3jr+jCmahLaHlseUprRrGlcgbu/fw4kaxsNOGMHIaETxJ9zcl++d/juLlo/q0ypBCm6iAhlDGgDjNuXDSC+QryCXEA8wVxcf7efTcu61hDNL1wWy3i7eLbSv8uFWYtZsSxdGbhl3NTV4lnoRlyLDicu+8h5X2rAvI9udNO0zMImmH0TZw/aGP0iVtXyybRXdJnOXTMl20wtc1GYotZL8XrEQ8i2mJ9l/WGTl5v3x9IUVb0+Bqu6+vQ3b/S/Z/vwZu+/ceXhp222uyubP9VKNy9lY1xhXZGmlRHdBl0Jib/8VBZefhSfSn6EQeRHahT5URJWfpQFlF8P2xgfOi2GSextfJYR3Pgs80TGZzMdZ3wwxIQxviEWghqf5aF/vWFYmwD1huRU9YYsgNPABOMRnMZiMWy9UR10mq+3EkFRYq9Sm6hFoFQDLb4PSdPy1X7vsxbw1+Nq6UiAXcrlIyRXuHwk+emWnyjdI1s+JXdQLZuqgCNaPk6G06yi/89mfEDqLTuVB5cdwYlkRzKE7IjGkB2lQWVH+UHZffkBaCHSXpWkZCMb5FmakGKbFR/BNis+0rPJ8hPt67FsinJpsXyq5KiGj6Nwqum9ZmhWbADtnOb5CPYwz0d6zvL8RPt6JJ/i0iOZVPv/gNUj+bjDcx2ftfP0gY9gHz6wkeDZ4viJ9rU4PsWlxfGpmXdpcHiG418aHHrEWKVBClEaTMcoTX/eHOgHLQ+cSM7/Ag==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [mud_id = _t, visitor_id = _t, session_id = _t, #"Time stamp" = _t, #"Page Name" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"mud_id", type text}}),
    #"Grouped Rows" = Table.Group(#"Changed Type", {"visitor_id", "session_id"}, {{"Events", each _, type table [mud_id=text, visitor_id=number, session_id=number, Time stamp=text, Page Name=text]}, {"Start Time stamp", each List.Min([Time stamp]), type text}}),
    #"Added Custom" = Table.AddColumn(#"Grouped Rows", "Abandoned Flow", each if Table.RowCount(Table.FindText([Events], "Hit Connect"))=0 then "Y" else "N"),
    #"Added Custom1" = Table.AddColumn(#"Added Custom", "No flow at all", each if Table.RowCount(Table.FindText([Events], "Select API environment"))=0 then "Y" else "N"),
    #"Added Custom2" = Table.AddColumn(#"Added Custom1", "Completed flow", each if Table.RowCount(Table.FindText([Events], "Projects Page"))<>0 and Table.RowCount(Table.FindText([Events], "Hit Connect"))<>0 then "Y" else "N")
in
    #"Added Custom2"

Data Summary

let
    Source = Data,
    #"Unpivoted Columns" = Table.UnpivotOtherColumns(Source, {"visitor_id", "session_id", "Events", "Start Time stamp"}, "Attribute", "Value"),
    #"Filtered Rows" = Table.SelectRows(#"Unpivoted Columns", each ([Value] = "Y")),
    #"Grouped Rows" = Table.Group(#"Filtered Rows", {"Attribute"}, {{"Count", each Table.RowCount(_), type number}})
in
    #"Grouped Rows"