Their docs (https://docs.gitea.com/installation/comparison?_highlight=is...) bring me to this GitHub issue, which suggests that implementing Kanban is in progress: https://github.com/go-gitea/gitea/issues/14710

Personally, I think it's great that the features are there (much like you also get with GitLab), but I might opt for a more specialized solution that has been around for longer. For some folks the coupling isn't an issue and is welcomed instead, though!

It actually does! It's called Projects.

Thus ends my search for a kanban board, since I already have Gitea.