Inspired by https://github.com/alexbowers/nova-categorise-resources . Makes nova core theme navigation collapsible using core functionality of resources "$groups". If you have lots of groups you might end up with a long list of resources. You can group them but again it will be a long list. With this package groups are displayed as collapsed menu items. All you need to do is keep using the "$groups" and install this package via:
composer require tanmuhittin/nova-collapsible-groups

Credits

https://github.com/alexbowers