for 16.1 we've made that a reality. <snip>There aren't many plugins yet <snip>User contributions are now key, and there weren't any (official ones) yet. <snip>
What does it take to write a plugin? https://docs.opnsense.org/development/examples/helloworld.html
I apologise for addressing a larger audience with this response. I felt this was necessary as it comes up quite a bit lately. If there are more specific questions we can gladly discuss them.