I just went through the same process with wanting to convert to Siri voice & HomeKit integration.
The switch was actually simple! No hardware at all! The actual setup took <30mins. I now have ALL Smartthings Devices in HomeKit - used for device control, automations, and Siri.
Home Assistant, setup on a VirtualBox running Ubuntu: Hassio with Docker.
- Hassio/Virtualbox: Video Virtualbox/Hassio setup/ Guide
- Install Smartthings integration, discover your devices.
- Strongly consider whether you want to use the direct integrations with HA or want to merely use HA as a bridge to Homekit, ie: if integrating Hue + ST separately - you may have to create new naming. You can also use “ignore” commands to get rid of classes/groups etc.
- Sign into Home Assistant Cloud Service (provides https, remote control, and Alexa/Google integrations). You have 30 days free so just try it.
- Once your devices “entities” are configured and your naming system is setup, just type “homekit:” into your configuration.yaml file and all of your entities will be discovered in homekit (can be used with Siri).
I was incredibly surprised with how easy it was! The problem now is the time spent customizing/integrating! I love having a new toy, and it has been fun playing with! I only have a few devices that Home Assistant wasn’t able to discover independently, so I’m investigating all of the integrations to verify whether HA itself is powerful enough to run without ST.