I personally did not find any app or settings which could easily do this, though this is not an app or gui, but its the simplest and easiest way at least for me.
By default NextCloud has index.php in the urls, it’s not a show stopper at all but it’s good to have nice clean urls when sharing.
Objective: To disable password based logins and login only using key based authentication. Will create a pem file which will be used to access the server. OS used is CentOS 7 64bit.