That only appears to apply to hard drives though.

If you want to use M.2 SSDs for your storage pool and cache, then you still need to use a Synology-certified SSD (which doesn’t necessarily mean that it needs to be Synology branded, just tested and certified).

From https://liliputing.com/synology-backtracks-and-adds-3rd-party-hard-drive-support-to-its-2025-nas-lineup-network-attached-storage/