Add this to .bash_profile to list all hosts from your .ssh/config file

.bash_profile

#list all hosts in .ssh/config
#if you add an argument, it lists all hosts that contain that word
whatssh(){
    if [[ $# -eq 0 ]]; then
        grep -w -i "Host" ~/.ssh/config | sed 's/[Hh]ost//'
    
    else
        grep -i "^Host\s\+.*$1.*$" ~/.ssh/config | sed 's/[Hh]ost//'
    fi
}