Exactly. Scottiestech's YouTube has some good info on how your smartphone is tracking you more than you think. Sometimes I think about building my own phone with a Raspberry Pi or use LineageOS.
AFAIK one of the best solutions for smartphone privacy is using a custom Android ROM without Google apps installed. Of course that means basically no 3rd party apps, but you can still get a surprising amount of functionality with just a web browser. You’ll still get tracked by your mobile provider, but I think that would happen even with a dumbphone.
> Of course that means basically no 3rd party apps
I'm using LineageOS without Play Store/Services and would like to dispel this myth. Here are just some of the third party applications I can install directly from the developer using adb, without going through a third party store: Signal, Firefox, NetGuard, NewPipe, Orgzly, OsmAnd, Tor Browser. Those pretty much cover all of my smartphone needs and more.
You can use microg. It's a Free reimplementation of google play framework, so that apps which depend on it can still function in a de-googled phone. It's imperfect, I admit it, and breaks some apps, but it's still a massive help.
I'll second (third?) LineageOS + microG! Full ROMs combining both are available [1] (OS updates often seem to have to be installed manually, but are supported on popular phones for years). In addition to using everything from the F-Droid repository, I can run Slack/Discord/Messenger/WhatsApp/GroupMe (though notifications are hit-or-miss) and a good few other apps (Duolingo, bank mobile apps, Uber but not Lyft). Many of these apps can be installed via Yalp Store [2], which is a frontend for the Google Play store with a built-in account to provide some anonymity. It'll do until I get a Librem5 [3].
TL;DR: no Google, most things work, but not necessarily smoothly. I've used it for a few years now.
You shouldn't have to find a half dozen toggles somewhere. there should be a master toggle somewhere that turns that crap off. Location, sync, listening, all that stuff. They could provide that if they were serious about privacy, but they don't
Certainly if you want to build your own Pi phone don't let anyone stop you, but if you want something very much like that but prefabricated, the pinephone is a good option.
I do use LineageOS+microg without play store installed, to avoid any Google software on my phone (yet still being able to use some apps which depend on the google framework)