October’s architecture makes extending any plugin a pretty straight forward process so don't worry if the plugin that you choose doesn’t meet your needs straight out of the box. Just find something close to your requirements and treat it as a starting point for creating exactly what you need.
Alternatively, you can create your own new plugin from scratch. October has an amazing system plugin to help you to create new plugins. It's called RainLab.Builder ( https://octobercms.com/plugin/rainlab-builder) and will dramatically ease the process of scaffolding your own plugin for use within your own, custom application. The process of creating plugins within October can be found within the official documentation at https://octobercms.com/docs/plugin/registration.
When creating your plugin October doesn't force you to use its built-in mechanisms. You can define your custom routing by creating a routes.php file in your plugin's directory if you wish, passing the request directly to your controllers (more information here: https://octobercms.com/docs/services/router).
Remember also that a plugin within October can be anything from a small enhancement to the currently existing functionality through to a large and powerful Web App using custom architecture and filled with the design patterns that you prefer to use. Once again the choice is yours.