AFAIK the only component that really relies on logind is GDM. If you don't want GDM and are comfortable using another display manager to launch your GNOME session, that should work fine, although I haven't tested this in a while. You may also be able to launch your session manually the old way, without a session manager, although that will probably require you to use setuid X which comes with the usual caveats. It's probably a total no-no if you're using wayland. If you decide you want GDM and wayland then you still don't need systemd-logind for session management, you can use elogind, or you can grab BSD's patches for consolekit support. The real issue there is that GDM requires some kind of session management, if you want to do this without any other daemons whatsoever, then you will have to reimplement parts of logind/consolekit inside GDM.

With the search services, there is a switch for that in settings under "Search."

With dconf, that is not actually integral to the toolkit. The API that applications use is GSettings, which requires a backend to actually store the settings, and dconf is just one of those backends. You can disable the dconf backend and just use the one that writes ini files to your home directory, or use some other backend. Technically apps can try to force the dconf backend but I've never seen one that does this.