Or, if we want to exactly match the original request, it is easy to transform to:

use Algorithm::Loops qw( NestedLoops );

sub expandSubLists
{
    my $av= shift(@_);
    return [
        NestedLoops(
            [ map ref($_) ? $_ : [$_], @$av ],
            sub { [@_] },
        ),
    ];
}
[download]

which, of course, chews up a lot of memory if given a lot of selections to generate.