A date for each record

Tough to say exactly because I'm not sure what you want. But, if you had that table and you create a Calendar table like:

Calendar = CALENDAR(DATE(2018,1,1),DATE(2018,12,31))

Then you could do this:

Table = GENERATE(productstable,Calendar)

It's a DAX solution, not Power Query.

In the query editor you would add a column with this formula:

List.Dates(#date(2018,01,01),365,#duration(1,0,0,0))

Just expand the column then.