How do you create keys for SSH in Hass.IO and where do you put them?

Yes, using the SSH & Web terminal addon instead of the SSH addon.

Keys generated (~/.ssh/) are persistent. Can be used for the workflow SSH into Hass.io -> SSH out of Hass.io.

However, if you need to have outbound ssh access from within a script or some such, the solution I’ve ended up with is to have a separate SSH key somewhere under config/.