This is likely to be insecure

install drawterm or conterm.

$ doas pkg_add drawterm

currently, drawterm doesn't ask for username on OpenBSD. however, you can emulate it easily.

$ cat /usr/local/bin/sshdraw.sh
echo -n 'user[glenda]:'
read duser
if [ $duser ]; then
        drawterm -r /var/empty -G -u $duser
        drawterm -r /var/empty -G -u glenda

create a user for connecting into, for example, "drawterm". then append the following to /etc/ssh/sshd_config

Match User drawterm
        ForceCommand sshdraw.sh
        X11Forwarding no
        AllowTcpForwarding no
        AllowAgentForwarding no