There used to be hook
SitesSidebar_SitesSidebarSites:Before to add elements int sidebar since 3.2.0 Releases - Local. Those are still present in the documentation https://build.localwp.com/building/hooks/content-hooks.
This was removed with release of version 6.7.0 When the “Starred” And groups were intrduced. Now we got version 8 and still does not work.
It used to work before. Now my element does not render there.
Or there is now other way to add elements into sidebar since we got this “Starred” group and Sites. - With addition of this feature the hook stopped to wrok.