I locked myself out of lightsail my ubuntu container

Would it help to use the startup script described in the document "An OS-level firewall is blocking SSH port access"?
https://repost.aws/knowledge-center/lightsail-resolve-ssh-console-errors
Try setting up the following script when creating a snapshot of Lightsail and booting from the snapshot.

sudo ufw disable
sudo iptables -F
sudo mv /etc/hosts.deny /etc/hosts.deny_backup
sudo touch /etc/hosts.deny
sudo systemctl enable sshd
sudo systemctl restart sshd