More interestingly, I only recently learned that you can add a ~/.ssh/rc to run commands on every ssh login. Are there other common useful rc locations people are aware of?

Can anyone give an example of a command I'd want to run on every .ssh login, but not put into my .zshrc/.bashrc on that machine?

You might want to curl the weather on your login with https://github.com/chubin/wttr.in I do this on my RPi