Region annotations with InfluxDB

Reviving this question.
I read Creating Grafana Annotations with InfluxDb | Max Chadwick example and other documentations. I have a system to store punctual and region events at the database, I want to show them as annotation on Grafana.

Still region annotation unsupported by InfluxDB backend?
If is supported now, what is the data point format to save? (better/recommended format)
If still not, could someone indicate a database the allows me to do?

I am adding the related topic here in the forum to see if I miss something