@john.c I've put this on the feedback portal as a feature request, so it doesn't get buried in a thread that started out about pool masters: https://feedback.vates.tech/posts/121/publish-build-date-and-package-manifest-sbom-with-the-xoa-xva-download .
As far as I know votes there help the team prioritise, so if you and @Forza want it, that's the place to say so.
There's an open PR adding SBOM generation (https://github.com/vatesfr/xen-orchestra/pull/10368), but going by the files it touches it covers XO's own JavaScript dependencies, not the Debian packages in the appliance.
I've only looked at the file list, not the code, so happy to be corrected. How often the downloadable XVA gets rebuilt, I still don't know: @Danp said back in 2024 that it isn't rebuilt for every XOA release (https://xcp-ng.org/forum/post/81220), which would fit the 2025.12 tag, but I'd rather not guess beyond that.