Welcome! Aurora store is a violation of Google's terms of service, don't login with your real account, you risk it being banned. I feel like if you're going to login with a self owned account you might as well do so through the play store, at that point the privacy implications are mild. Sure, information about what apps you use is then correlated to your account... and of course that you own a pixel but that's pretty much the end of it. Especially if you will login to YouTube anyway.
Have you considered YouTube alternatives like NewPipe? Subscriptions are stored locally on your device (I'd argue this alone is more worth protecting than what apps you have installed), really the only aspect you may miss is commenting.
awayfromspying Then, I guess if I'm using YouTube, technically Maps could still be tracking me, correct? Is there a way around that?
That would depend on the permissions you hand the two apps. If you only ever grant maps one time location permission when you use it it won't have anything on you for when you don't use it. Apps within the same profile can communicate with each other on mutual basis via ipc - interprocess communication. But given both will have network access by nature of their functionality this isn't a concern, just don't grant permanent location permission. Here too there are
solid alternatives available, Organic Maps, Magic Earth, OsmAnd.
awayfromspying For example, if I don't want to miss out on notifications, or run into other issues I can't think of right now, I'd probably just want to have these two services installed, right? I have a large list of apps I'm using and would prefer not to waste countless hours troubleshooting issues with each one
It's a good idea then, yes.
awayfromspying Also, what data can the 3 google services gather about me in the main profile, if they only have network permissions for notifications?
awayfromspying But because the google services don't have privileged access, I don't have much to worry about.
Indeed. It can't gather any more than any other app, so things like sim country code, list of installed apps, device model.