How to make Ubuntu 20.04 start without GDM and in multiuser shell mode with startx starting all normal session services such as the dock?

I'd like to start up Ubuntu 20.04 to a textual user login and shell like Server and then when using the system be able to start X for the user by just executing startx such that when you start it, the feature parity is essentially one-for-one with normal system usage (such as having the "dock" or app favorites that lives on the side).

I'm able to accomplish most of this with the following:

sudo systemctl set-default multi-user
sudo reboot

At this point I can login with multi-user mode and execute startx to get a fairly vanilla session, but there's no dock (or whatever Gnome calls the side / favorites bar).

How can one control which services start that are necessary to have mostly a normal system starting with startx?