@peterxian, @D34DC3N73R,
Switching openthread/otbr with ghcr.io/ownbee/hass-otbr-docker did the trick. Ideally I would like to stay within the “official images”, but that would work for now.
Here: Running OTBR in Docker - #3 by D34DC3N73R
So now what should be the next step when Thread and Matter integrations are configured?