Storing and reusing a value as a variable/parameter for other queries

You can just filter the query for the Excel data to just a list, and then instead of making a proper "parameter" from the GUI, just refer directly to the query as the list parameter. So if the query with your list from Excel is named "FilterList", then your other queries can use it as a parameter like:

let Source = SomeTable

ApplyList = Table.SelectRows(Source, each List.Contains(List.Buffer(FilterList), [ColumnNameBeingFiltered]))

--Nate