Holy crap, I never knew about this before, but this is awesome.
The command is drush uli
It's got options,
namefor the usernameurito specify the url of the site (our weird setup requires us to specify the url of our site)
ex: drush uli --name=rootid --uri=http://midpen-openspace-d8.test
A window popped up that led straight to the user page, with its "reset password" fields! I'm using it on my local, so I'll need to redo if I pull the database from Pantheon, but I'm only doing this cause Jason's out of town so there aren't any changes to pull anyhow!