For example, I have a library written in Ruby, documented with YARD.
The library is not in the form of a Gem, but rubydoc.info can pull it off GitHub: Ruby code -> rendered docs.
For Python/Sphinx, I think ReadTheDocs does the job. Random example: RST Python source -> rendered docs.
Is there a similar service for Perl/POD?
No. There is no such online service in the Perl ecosystem. Github can render standalone POD documentation, so it would make sense to put it there.
For the inlined POD, your users will be able to use the
perldoc command once they have installed your code on their system. Some users might also have a local perldoc-to-browser tool installed, but you cannot influence that obviously.