is it possible to use client certificates in Nextcloud to autenticate the users against the Nextcloud instance? I know that i can restrict the access to the Nextcloud-loginsite only to users who installed the certificate, but it is possible to distribute the certificates to the clients, so they can access their files in Nextcloud without usin their credentials?
A lot of years ago i tested client TLS/SSL certificates with apache2 and it works fine. I think it is also possible additional to server certificate e.g. Lets Encrypt to use client certificates. The apache2 (https/tls layer) is not corresponding to nextcloud functions. But i do not know if it is possible to fully deactivate the nextcloud login process (search perhaps SSO options). Hopefully you do not use a nextcloud client (windows, linux, macos, android, ios). I think that does not work together with enforced client certificates.