Since FreeBSD's bhyve hypervisor didn't provide SMART for RDM, There a patch for this.
You can specify SMART Info of Host's disk to virtual AHCI disk. that will make DSM recognize it.
You can get the patch here: https://reviews.freebsd.org/D25975
Without patch and specify passthrough SMART device, DSM cannot tell SMART.
After Patch and sepecify a SATA SSD as the passthrough device. here is the SMART result.
Since my M2 SSD is not in SMART database, the attribute are not showing correctly.