flighty_sloth I have tested this quite a bit, with Google Location Services ON, so I can tell what Google gets ahold of. I can tell you with high confidence that using Google Maps with locations requests rerouted to the OS is an effective way to block what makes its way to your location history!
I used Google Maps quite a bit for a whole month with Location History ON and had absolutely 0 data saved in said location history. GPS and Google Services Framework didn't have location on, or nearby devices and scanning was disabled. I don't know if having those enabled would allow for GPS to get location history from scanning, I only tested GPS use.
After a while I disabled Reroute located requests and gave GPS location permission, and instantly it showed up on location history! I turned it off at that point and deleted the data. Felt better that I did it in a public place as well, though I do have to think that the paranoia over Google never actually deleting your data might be a bit overblown... Nevertheless I still follow best practices just in case...
One thing I did not test was navigation mode in Google Maps! I don't own a car currently, so haven't had the chance... I do remember hitting it by accident and seeing the disclaimer that seems like it pops up on first use saying it WILL use your location and speed for it's traffic data. Whether that makes its way onto your location history, gets paired with your Google account, profile, (if there even is a personal profile on "you" separate from a Google account I doubt, would be kinda pointless for their use as an ad company) or if GPS has Nearby Devices permission if it tries to connect to the vehicle's built-in telemetry system for better tracking, I have no idea. I doubt anyone outside of higher ups and some engineers at Google even know the answers to that question!
I do really think that the whole "inter-app communication sending heaps of data to Google" thing is a bit overblown... I don't think (but u haven't found proof either way yet) that IPC wasn't designed to bypass network blockage for just one app, so that app will use IPC to reroute that pending and blocked info to another app that has network access! In the stock OS, you would loose network in poor signal areas or when Airplane Mode was on. Apps are designed to buffer their data to send when connectivity resumes. THAT I do know.
In the stock OS, you cannot block network for apps one by one! Why would apps be designed for that scenario? Just in case they made their was to GrapheneOS, a system with a paltry 200k users, vs the well over 1-2 billion Android users? I doubt it!
Also almost all the tracing services, providers, and receivers I've seen, are about app measurement... That's about it, just analytics on how apps are used.