I did try this and used it quite a bit at Namati, and I use it here on meta too. It’s pretty handy actually to know if colleagues in the group message or the person we are engaging within that message has actually seen the message. So I like it and do take advantage of it.
The OP is more an inquiry about the extent to which we can have parity with a whatsapp feature, which is purely technical… did the message reach their phone? Did it get opened on the phone? It’s not so much trying to evaluate whether the person took the time to cognitively take in the message and understand it. I know that type of data is kept in discourse as well (e.g. time spent reading in a topic) but that’s not what I was asking for back then.
I know discourse is not a phone app like whatsapp and totally understand that we can’t really expect to know the moment someone has been notified and if they have seen the notification in their email.
That said, there are definitely cases when you might want to invite people to a group so they can participate in some time sensitive discussions and receive materials on a timely basis. At Namati the biggest challenge was organizing an annual leadership course - people had to receive course materials ahead of time and do some small assignments in preparation for the course. There were also logistical details they needed to receive and deal with. It was a frustrating challenge to get them to engage.
Maybe a discourse group option could be contemplated to make this happen. E.g. if you are in this group, show that you have received and read posts in that category.
Then again, we now have the Discourse Policy plugin and Namati could use that to 100% make sure people respond.