Do not use sudo for FreeBSD. I tested sudo for FreeBSD and despite, that it is widely used in online procedures and documentation, I had to conclude, that it is somewhat poorly documented and simply does not work properly for FreeBSD.
# visudo
david ALL=(ALL) NOPASSWD: /usr/sbin/service nginx onestart
One thing, in particular, that did not work, was the ability for a member of the wheel group to execute a trivial safe command as root without the requirement for a password. sudo kept asking for password.
$ id
$ sudo service nginx onestart
Password:
sudo: a password is required
I recommend deinstalling sudo and instead using security/doas. This is also recommended on the FreeBSD Forums.
# rm /usr/local/etc/sudo.conf
# rm /usr/local/etc/sudoers
# pkg remove sudo