Does routeros support 3rd party development of plugins? Looking to create a plugin to send info off-site.
No, ROS doesn’t support 3rd party plugins.
ROSv7 will support running containers, but that might not help solving your problem.
A soultion could be to use RouterOS scripting to deliver the information.
In addition, it’s possible to trigger scripts for user-defined events with the built-in service Netwatch. For details see https://wiki.mikrotik.com/wiki/Manual:Tools/Netwatch.