Most of the items of the agenda page are already done; a few elements are moved to postponed, i think, there is just one open item. The largest missing effort is the usual release work (summarizing the changes, documentation updates, testing, packaging, ...).
There is no paved way to cherry pick all the CSP and security improvements from oacs-5-10. The basic CSP infrastructure is already in OpenACS 5.9.1. The forthcoming release contains numerous changes especially in the application packages (also some core improvements). I would expect that for ]po[ most work will be the adoption for the application packages which are not part of the ~100 packages of oacs-5-10. Adoption means here to disallow "javascript:" URIs, or "on*" event handlers (see e.g. [1]) for build restrictive CSPs (certain features can be selectively allowed in case on dependencies on external packages, but the default should be restrictive).
all the best -g
[1] https://openacs.org/xowiki/CSP