Hi @samflyn ,
When you hit /aem/start.html below are the servlets and script will execute in order of preference for method for given method:
- /libs/granite/ui/components/shell/page/page.jsp
- org.apache.sling.servlets.get.impl.DefaultGetServlet
- org.apache.sling.jcr.webdav.impl.servlets.SlingWebDavServlet
Similarly for /crx/packmgr/service.jsp
- org.apache.sling.servlets.get.impl.DefaultGetServlet
- org.apache.sling.jcr.webdav.impl.servlets.SlingWebDavServlet
You can check all such process here http://localhost:4502/system/console/servletresolver

Additionally, You can also get some more details by installing x-ray mode where you can see which all scripts are processing by navigating to any AEM Touch UI pages like /sites.html, /assets.html, and /aem/tags in x-ray mode. For more details please visit article [0].

[0]: https://www.bounteous.com/insights/2020/12/12/inspecting-aem-admin-ui-components-ease
Hope that helps!
Regards,
Santosh