In the course of tinkering with Hook over an issue with Drafts, I reinstalled Hook on my machine and found something weirdish about the script bundle.
Before uninstalling, Hook was telling me it was up to date (build 2552) and the script bundle was also up to date (61).
I had my doubts, because @LucB had just announced that Quiver was available in 61, yet I didn’t see it.
Lo and behold, after uninstalling and reinstalling the (purportedly) same version 2552 + bundle 61, I now have many many more apps available (including Quiver).
So I believe there may be an issue where Hook thinks it’s installed the latest bundle yet hasn’t
(Also, didn’t solve my Drafts issue, but Yeah, I have Quiver OOTB!)