I echo that thanks!! Also thanks for the pointer to the patchset, @agners. That was the key for me.
For those who are running a standalone OTBR and are too impatient to wait for Agners’ PR to be merged upstream (like me), you can simply apply the patchset manually to get this working:
git clone --depth=1 https://github.com/openthread/ot-br-posix.git
cd ot-br-posix
curl -s https://raw.githubusercontent.com/home-assistant/addons/master/openthread_border_router/0001-Avoid-writing-to-system-console.patch | git apply
curl -s https://raw.githubusercontent.com/home-assistant/addons/master/openthread_border_router/0001-rest-implement-REST-API-to-get-dataset.patch | git apply
curl -s https://raw.githubusercontent.com/home-assistant/addons/master/openthread_border_router/0002-rest-support-state-change.patch | git apply
git diff --name-status
# Then proceed with normal installation steps for your platform. For example:
./script/bootstrap
INFRA_IF_NAME=wlan0 ./script/setup
After this the dataset API should be working (try http:<otbr ip/host>:8081/node/dataset/active to test), and you should be able to add it to Home Assistant (enter http:<otbr ip/host>:8081 as the URL to the OTBR API).
A word of caution: I imagine this is very likely to break during a future upgrade given the differences between the patched API and what will eventually be merged as @Joe_Saiko called out.
Excited to play around with this!