Key pair generation
In git bash :
$ ssh-keygen -t ed25519 -C "email@mail.com"
Install and start ssh agent
In an admin elevated powershell :
> Get-Service ssh-agent | Set-Service -StartupType Automatic -PassThru | Start-Service
...
> start-ssh-agent.cmd
...
> ssh-add.exe ..\..\Users\XXX\.ssh\id_ed25519
Configure git bash
ssh-add ~/.ssh/id_ed25519 # if not done previously
git config --global core.sshCommand C:/Windows/System32/OpenSSH/ssh.exe
cat ~/.ssh/id_ed25519 # to add to https://github.com/settings/keys