For what it's worth, one can take systemd services and convert them into service bundles that run under a service manager on FreeBSD. Or use one of several hundred service bundles that have been done for you for various softwares. There is also a per-user service manager.

* http://jdebp.uk./Softwares/nosh/

* http://jdebp.uk./Softwares/nosh/worked-example.html

* http://jdebp.uk./Softwares/nosh/guide/converting-systemd-uni...

* http://jdebp.uk./Softwares/nosh/guide/per-user-user-services...