Just a story about a friend of mine in the Boston area. He went ahead and purchased the Home Assistant box and 25 Inovelli White dimmers (Matter/Thread). He also got the ZigBee USB stick and programmed it for Thread Border Router use.
Setup should have been easy, install the HA app, sync up the security keys in the app and start the inclusion process. Well it’s been 8 weeks and still cannot get the switches to include. All the experts on the HA board couldn't help, reddit couldn’t help. He sent me one of the switches and I got it to pair with the Hubitat though my HA Thread Border Router as a dimmer.
Well he bit the bullet and got a Apple TV that has the built in Matter/Thread and within 10 minutes had it paired with Apple and then right after that shared the pairing with HA.
Weeks of trial and error and $250 later he now has it working. What a nightmare.