You can install Homebridge your Synology DSM 6 / DSM 7. I use a Rasbarry Pi even though I own a Synology NAS. I didn’t want to mess up my NAS if something went wrong during the installation and I had a RaPi 3b just laying around. 
Then you need your HE to communicate with Homebridge. I use a method from dan.t and it has worked flawlessly since day one.
You also mention HA in the topic. For devices that HE dosnt support, I use HA with this integration from jason0x43. Has also worked flawlessly since day one. You can install HA on your NAS.
