Matter and Thread are different. You can use Matter over a number of different network types. (WiFi, Thread and I think Bluetooth)
Thread is a radio protocol (very similar to ZigBee) and you can run Matter over Thread but you need something called a Thread Border Router to sit between your network and the Thread network (just like a hub or Z2M does now).
So matter over WiFi doesn’t need anything dongle (other than WiFi). Thread needs a border router which could be a dongle or something like an Alexa or Apple TV etc.
A communication protocol for IoT devices
Thread is a low-power mesh networking standard for IoT devices. The low-power aspect is important for battery-powered smart home devices. However, it’s also low-bandwidth, making it ideal for applications that don’t send a lot of data, like switches or motion sensors.
Thread uses the same RF technology as Zigbee (IEEE 802.15.4) but provides IP connectivity similar to Wi-Fi. Unlike Zigbee, Thread by itself does not allow controlling devices: It is just a communication protocol. To control the Thread devices, a higher-level protocol is required: Matter or Apple HomeKit. Thread devices use the IPv6 standard to communicate both inside and outside the mesh network.
You can read about Home Assistant integration here.