Configure sshfs without a shell user.

1. Create a user without a shell and set a password for him:

# useradd -m "sshfsuser" -s /usr/sbin/nologin
# passwd sshfsuser

2. Open /etc/ssh/sshd_config and find the line:

Subsystem sftp /usr/lib/openssh/sftp-server 

Change it to:

Subsystem sftp internal-sftp

Also at the end of this file append the following:

Match User sshfsuser
    ChrootDirectory %h
    X11Forwarding no
    AllowTcpForwarding no
    ForceCommand internal-sftp

3. Restart ssh daemon:

# systemctl restart ssh

4. Change the ownership of the user's home directory. It must be owned by root for chroot to work:

# chown root:root /home/sshfsuser

5. Create a directory which sshfs will mount and change ownership:

# mkdir /home/sshfsuser/sshfs_dir
# chown sshfsuser: /home/sshfsuser/sshfs_dir

6. On remote server create a directory and mount sshfs there:

# mkdir /root/sshfs_dir
# sshfs sshfsuser@server_ip_here:/sshfs_dir /root/sshfs_dir

7. Check mounting:

# df -h

You also can configure fstab, key-based authentication, etc.