You can overload array deref. So you could write a class that overloads @{} to return an object of another class also overloading the operator, which finally returns an array constaining the desired element(s), enabling syntax like

my $element = $matrix->[$y]->[$x];
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I'll come back later today to add some proof of concept code. Of course you do take a speed hit and the resize restricition doesn't go away, but this would seem to be a case of trading speed for memory anyway.

Makeshifts last the longest.