Is this what you asked for

let
Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
Group = Table.Group(Source, {"Project#"}, {{"All", each _},{"Sugg_Start_Date", each List.Last(_[Sugg_Start])},{"First_Start_Date", each List.First(_[Sugg_Start])}}),
Expand = Table.ExpandTableColumn(Group, "All", {"Date", "Sugg_Start"}, {"Date", "Sugg_Start"}) 
in 
Expand

Or You can continue even without Expand Step if you need summarised result.