> Python can let objects be used as keys in dictionaries.

In Perl 6 object hashes allow you to do the same (https://docs.perl6.org/language/hashmap#index-entry-object_h...). If you're only interested in checking for existence, you can use a Set (https://docs.perl6.org/type/Set). If you want to just count the number of occurrences, you can use a Bag (https://docs.perl6.org/type/Bag).

> Perl's optional variable declarations catch a lot of minor bugs.

In Perl 6, variable declarations are obligatory by default.

> Python's iterators/generators take a lot of work to replicate in Perl.

In Perl 6 there is an easy to use interface for creating iterators (https://docs.perl6.org/type/Iterator)

All of these features are built-in, so no module loading is necessary.