You must use IKEA TRÅDFRI Gateway to add your drivers. Philips Hue Bridge can add TRÅDFRI drivers but they won’t appear in your Home app. That means TRÅDFRI drivers with Philips Hue Bridge won’t work with HomeKit. So dig into your pockets to buy a TRÅDFRI Gateway.
After you setting up your TRÅDFRI Gateway with IKEA Home smart app. The app will force you to add a controller (Wireless Dimmer, On-Off Switch/Dimmer, etc.) to control any smart accessory. That prevents you from adding any driver directly to the app. You have to add the driver through a controller. So again, dig deeper into your pockets to buy a switch/dimmer. I recommend TRÅDFRI Wireless dimmer. I just bought one as the device adoptor since I won’t use it to control my accessories.
You can pair the wireless dimmer with more than one drivers. When you push on/off on the dimmer. All paired drivers will respond. It’s okay if you just use it as the device adoptor like me. But if you want to use it later as a normal dimmer. Just remove it from the app and re-pair it the right driver.
Don’t buy any other IKEA smart accessories at the time of writing. Like motion sensors, bulbs, etc. Blinds are okay but reported the motors are louder than other brands. That means most of them suck.