That doesn't work.

It doesn't work with UNIVERSAL::can, but it could work with an overloaded can:

{
    package Foo;
    my %meth = (
        foo => sub { print "Foo?\n" },
        bar => sub { print "Bar!\n" },
    );
    sub baz {
        print "Baz.\n";
    }
    sub can {
        $meth{$_[1]} || __PACKAGE__->UNIVERSAL::can($_[1])
    }
    sub AUTOLOAD {
        use vars '$AUTOLOAD';
        (my $methname = $AUTOLOAD) =~ s/.*:://;
        $meth{$methname}->(@_);
    }
}

for (qw(foo bar baz qux)) {
    if (my $cr = Foo->can($_)) {
        $cr->();
    } else {
        print "Cannot $_\n";
    }
}
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