Synology started out having its own brand of RAM for as long as I can remember. I covered them back in 2017. After that they went on to have its own brand of M.2 NVMe SSD (SNV3000), SATA SSD (SAT5200), and SATA HDD (HAT5300).
One of the reasons Synology introduces their own lineup of SSD and HDD is for compatibility. The SSD and HDD are optimized for use with their own Synology NAS with customized firmware. Also, when things go wrong, the users don’t need to contact different vendors. They can bring it all back to Synology.