I maintain a LR cloud database, a hardrive folder that contains the edited files from LR, a Google Photos database that contains the best shared photos and a hardrive file that contains the raw images sent to LR. Hardrive folders are duplicated on a freestanding SSD.
Do you back up the SSD to an HDD? As far as I know, an SSD can fail without warning and data is not recoverable. With an HDD you often get a warning that somthing is going wrong with it making noises - and in the event of failure data con usually be recovered.