Previously auto-loading of USB drivers was driven by /etc/devd/usb.conf. Since latest release of FreeBSD this configuration file was removed and does not have an effect in favor of a newly introduced facility for this called devmatch. Legacy TrueOS 18.03 was apparently based on the FreeBSD 12 build prior to the devmatch commit was merged because auto-loading used to work there.
So far I gathered there are is a couple of items:
Update Trident Core devd overlay to configure devmatch if it is to be provided from Trident
devmatch service seems to be not migrated to OpenRC yet. This is the service: /etc/rc.d/devmatch
Previously auto-loading of USB drivers was driven by /etc/devd/usb.conf. Since latest release of FreeBSD this configuration file was removed and does not have an effect in favor of a newly introduced facility for this called devmatch. Legacy TrueOS 18.03 was apparently based on the FreeBSD 12 build prior to the devmatch commit was merged because auto-loading used to work there.
So far I gathered there are is a couple of items:
TrueOS repository appears to have OpenRC devmatch configuration but I don't find it anywhere in the latest Trident installation, e.g.: /etc/devd/ /usr/loca/etc/devd /usr/local/etc/devd-openrc https://github.com/trueos/trueos/blob/trueos-master/sbin/devd/devmatch-openrc.conf
The brief explanation with the commit reference can be found at the following bugtracker https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=234916
There is a more detailed BSDCan 2018 presentation on devmatch: https://www.bsdcan.org/2018/schedule/attachments/459_bsdcan2018.pdf
Here is the respective issue raised on FreeBSD bugtracker to get more input on the change in behavior: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=235257