I mainly used this list https://github.com/awesome-selfhosted/awesome-selfhosted#tas...
I did focus on "Task management/To-do lists", while OpenProject is listed under the "Project Management" section. This is likely why I missed it as I've been looking for something clean and simple (not JIRA) that is more akin to the earlier versions of Trello (rather than the feature bloated whale it has now become).
Looking at it now and to be honest it doesn't quite look like what I'm looking for when looking for a Trello alternative, I just want cards on a board I can move around (with a bit of metadata)