Hello,
As you may know, POSIX.1-2024 was published last year by The Open Group and the IEEE. (Ratification as ISO/IEC 9945 is ongoing however.) This is the first major revision since 2008; the revisions between now and then have been only to address errata. This version has new interfaces and removes old ones so getting this incorporated would be helpful. An unofficial web version is at https://pubs.opengroup.org/onlinepubs/9799919799/

No new archives have been published at https://www.kernel.org/pub/linux/docs/man-pages/man-pages-posix/ and I think cooperation with the Linux man pages folks will be needed here. Going solely off of memory, I get the impression that the Linux man pages folks asked The Open Group for special permission to curate and publish these. I know that nowadays The Austin Group keeps the standard in a private GitLab instance and I think they use AsciiDoc as this guide would hint for publications by The Open Group generally: https://pubs.opengroup.org/handbooks/gitlab-development/index.html
Research into how these manual pages have been created in the past would be nice; I've done very little so far. If no one upstream plans to work on this, I might be able to step in.