As long as Synology does have NDMP protocol, there can be no direct support for any backup vendor.
See this Synology forum post:
You can backup Synology as CIFS shares.
Are you wanting to use it as a source (to be backed up) or as a backup target (destination)? Either way, it should work fine. Plenty of other Synology models are on the HCL as a B2D target. Getting listed on the HCL is not a requirement for the B2D section.