I use SSH for authentication. I prefer gpg for signing commits.
https://docs.github.com/en/authentication/connecting-to-github-with-ssh/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent
ssh-keygen -t ed25519 -C "your_email@example.com"
Since I use multiple SSH keys, make sure to give them a descriptive name rather than leaving it as the default id_ed25519.
cat ~/.ssh/id_ed25519.pub
Copy its content.
When generating an SSH key on Termux, it’s easier to open Android Studio, browse the connected device (could be over WiFi), and copy the contents of this file under /data/data/com.termux/files/home/.ssh/id_ed25519.pub. Or simply double click it to open in AS, then copy its content.
Go to http://10.0.0.220:3000/user/settings/keys Add Key Paste the public key
In retrospect, I could have also just cat its content, and paste it into the browser on my phone.