@forteller these static entries are Desktop Actions, which are a FreeDesktop spec: https://specifications.freedesktop.org/desktop-entry-spec/latest/extra-actions.html
Dynamic actions aren't currently part of the spec, but are implemented on many desktops with the Unity LauncherEntry API. I hope that support will be added to GNOME either for this API or another one, specifically because that’s something we identified as missing from the Background portal as a replacement for status icons.