There a number of undocumented commands for Gondor, and I hate asking in IRC multiple times, so I’m starting this list. Please feel free to put more in the comments. I’ll add them as I discover more.
Create a new production instance on a stack:
gondor create --kind=production <instance-name>
Set an env var:
gondor env:set [instance] VARIABLE=var
instance is optional here, it will set it globally if not supplied.
Read env vars:
gondor env [instance] [VARNAME]
both instance and VARNAME are optional, using without instance will just show global vars, and without VARNAME will show all env vars set for the instance or globally.