To enable HomeKit control for your Shelly devices, you can utilize the Matter bridge plugin, which extends compatibility across Shelly’s Gen1, Gen2, and Gen3 product lines.
Link to the plugin: https://www.npmjs.com/package/matterbridge-shelly
For Shelly Plug S (Gen3), which is a certified Matter device, it offers seamless integration and works natively with HomeKit without the need for additional configuration.
All GEN4 devices are Matter certified too.