@mayel OK, I've given it some serious thought and have created two issues to track this work:

https://github.com/go-fed/activity/issues/65

and

https://github.com/go-fed/activity/issues/66

In all honesty the work is larger than my gut feel (isn't it always?!) so I've scheduled it as part of the next major version release. I don't have a great sense as to when that will be (on order of months given my current life schedule) so I understand if you eliminate go-fed as a choice because of that.