Generate an SSH key, delegate a subdirectory for it, and add it to your SSH agent. Uses ED25519.

ssh-gen.sh

#!/bin/bash
echo : Configure
echo
echo -n "Subpath: "
read SSHK_DIR < /dev/tty
echo -n "Comment: "
read SSHK_COM < /dev/tty
echo

if [ -z "$SSHK_DIR" ]
then
    echo Invalid parameters. Exiting...
else
    if [ -z "$SSHK_COM" ]
    then
        SSHK_COM="$SSHK_DIR"
    fi

    echo : Generate
    echo
    mkdir "$HOME/.ssh/$SSHK_DIR"
    ssh-keygen -t ed25519 -a 100 -C "$SSHK_COM" -f "$HOME/.ssh/$SSHK_DIR/id_ed25519"

    if [ $? -eq 0 ]
    then
        echo
        echo Key created: $HOME/.ssh/$SSHK_DIR/id_ed25519
        
        if [ -z "$SSHK_NOCHAIN" ]
        then
            echo
            echo : Add to key store
            echo
            ssh-add "$HOME/.ssh/$SSHK_DIR/id_ed25519"
            if [ $? -eq 0 ]
            then
                echo Added successfully.
            else
                echo Issues encountered when attempting to add to key store. Retry manually.
            fi
        fi
    else
        echo
        echo Key creation failed.
    fi
fi

To run:

curl https://gist.githubusercontent.com/ChlodAlejandro/0cf80eeefd79cf4686626d8d5312afbe/raw/ac9aa5b330279fef42fca87f17142d289e533f90/ssh-gen.sh | bash