You should be able to integrate your IKEA and Homekit devices into the one if you use HomeAssistant.
The IKEA Tradfri system is all Zigbee based - I have a bunch of their light bulbs and strips, plus a few smart power plugs. I personally have them attached to my own Zigbee controller, but there's also a Home Assistant Tradfri integration if you want to keep using their Smart Hub controller.
There's also a Home Assistant homekit integration, so you can use HA to orchestrate events happening on the Tradfri side to trigger something in the Homekit side, or vice versa.
(I don't have the Tradfri smart hub or Homekit devices, so YMMV on specific possible options)