This is correct more or less. The Ikea hub has had the ability to bridge its zigbee devices to Matter for a while now. So in my case, Apple Home has no idea my lights and switches are not Matter, they just show up there even though they are actually zigbee.
Ikea recently did an update to enable the hub to be a Matter controller itself (over thread or Wifi). This means you can add matter devices to the Ikea hub directly and use the Ikea Home Smart app the control them instead of Apple Home or etc. You can add non-Ikea matter devices as well as Ikea matter devices (when they are released).
* The old Ikea Zigbee products will remain Zigbee. They will still require a Zigbee coordinator.
* The new products will be Matter-over-Thread. They require a Thread coordinator (or whatever the Thread equivalent is called).
* The existing Ikea hub has had a firmware upgrade that allows it to be simultaneously a Zigbee and Thread coordinator.
* The Ikea hub adds a Matter compatibility layer to the devices that don't natively support Matter.