Unfortunately, that notation doesn't work. Perl5 isn't Ruby (yet).

You'll need to unroll the array somehow. I'll leave it up to you to decide if the following is a readable solution:

@uniq{ map { $_->[-1] } @AoA } = ();
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Update: of course, when we're going that way, we might as well be explicit about it and just say:

my %uniq = map { $_->[-1] => 1 } @AoA;
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