I see the last message there goes back to august of last year. Is there anything in your pipeline concerning certificate and user/password authentication?
Currently, there is https://gitlab.com/bitfireAT/davx5-ose/-/merge_requests/13/diffs
However, it would require UI changes, which are always very complicated and have big impact. So at the moment, it’s on the idea list, but there’s no priority for that.