ssh-keygen -t ed25519 -a 100 -C "your_email@example.com"
The -a 100 option specifies 100 rounds of key derivations, making your key's password harder to brute-force.
Multiple keys and repos: https://blog.touret.info/2018/11/16/gerer-plusieurs-cles-et-plusieurs-repo-git/
Cloudflare Tunnel: https://orth.uk/ssh-over-cloudflare/
https://grahamhelton.com/blog/ssh-cheatsheet/
https://news.ycombinator.com/item?id=37886049
https://nickjanetakis.com/blog/using-a-custom-ssh-key-to-access-a-private-git-repo
Visual guide to SSH tunneling and port forwarding: https://ittavern.com/visual-guide-to-ssh-tunneling-and-port-forwarding/