There are no username and password options for nfs mounts. Per the mount man-page:
Mount options for nfs
Instead of a textual option string, parsed by the kernel, the nfs file
system expects a binary argument of type struct nfs_mount_data. The
program mount itself parses the following options of the form
‘tag=value’, and puts them in the structure mentioned: rsize=n, wsize=n, timeo=n, retrans=n, acregmin=n, acregmax=n, acdirmin=n,
acdirmax=n, actimeo=n, retry=n, port=n, mountport=n, mounthost=name,
mountprog=n, mountvers=n, nfsprog=n, nfsvers=n, namlen=n. The option
addr=n is accepted but ignored. Also the following Boolean options,
possibly preceded by no are recognized: bg, fg, soft, hard, intr,
posix, cto, ac, tcp, udp, lock. For details, see nfs(5).
You will probably have to write a wrapper in order to do this via NFS.