From what I understood in the ticket ( I haven't confirmed independently) it's the later. You can set an environment variable to move the .pi directory ( into your XDG Config dir) but it's both the cache and config combined.

Quick Edit: Since github is back up, heres the comment I was referencing: https://github.com/earendil-works/pi/issues/534#issuecomment...

Ah thanks. I see the problem now. In fairness, it doesn't concern me personally very much, but the refusal to engage is not great.