Alleluia!
I was able to try the thing I saw on YouTube and on the reference link, that is, forcing IPv6 in the network settings of HA to dynamic on my Home Assistant instance, and it works:
I was able to add my Aqara M100 hub + 5 Ikea Matter/Thread devices in 10 minutes (it’s veeeery slow!) and all devices are controllable and report everything 
All device firmwares have been upgraded.
Now