I am describing the “user’s configuration file (~/.ssh/config)”, in the link you gave
Here’s an example from one of my ssh qubes (non split-ssh qube setup)
# content of ~/.ssh/config file
Host myvps
User user
Hostname somelong.onion
IdentityFile ~/.ssh/myvps_ed25519
Once I have this file, in my ssh qube (again, non split-ssh), I simply do the command
ssh myvps
and the ssh stuff automatically uses my username and hostname (ssh target) strings.
So, where does this file go? Because, with split-ssh setup, the IdentityFile (ie, the ssh privkey) is located in the vault qube, and not on the ssh-client qube. So, on ssh-client qube, the ~/.ssh/myvps_ed25519 would be a non-existent file?