Osram, Hue Bridge and Homekit not working

Hi

I have a Hue bridge V2 without hue bulbs

I'm using Osram Lightify bulbs instead.

The bridge works without problems with Osram bulbs and I can control them from all kinds of apps.

I paired them to a SmartThings hub and I can control them from the SmartThings app.

I can control them with the Hue app.

I can control them with Alexa (via Hue or SmartThings).

But I can't control them with Siri.

I talked with Philips Hue support and they told me this is a limitation by Homekit.

so my question is why are you doing this?

I understand why I need a hub that supports the HomeKit protocol

I don't understand why devices controlled by this hub (using zigbee protocol) should be approved by Apple.

Thanks