Create an Ed25519 or RSA 4096 SSH key pair right in the browser (the key never leaves your computer) and build a ~/.ssh/config block: alias, port, key, ProxyJump, port forwarding, keepalive.
Everything runs in your browser; nothing is sent anywhere.
Is it safe to create a key on a website
The key is made by the browser’s built-in cryptography (WebCrypto) on your computer and is not sent anywhere; you can verify that in the developer tools Network tab. For maximum caution use ssh-keygen -t ed25519 -C "comment" in a terminal: same result. Once key login works, turn off password login on the server: PasswordAuthentication no in /etc/ssh/sshd_config. Is SSH open from outside: port check.